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Simple database (view source)

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Applesoft BASIC
(file format, schmile format)
(Applesoft BASIC)
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{{draft task|Simple Data TrackerStructures}}
 
;Task:
Write a simple tool to track a small set of data.
 
The tool should have a commandline interface to enter at least two different values.
The tool should have a command-line interface to enter at least two different values.
 
The entered data should be stored in a structured format and saved to disk.
 
It does not matter what kind of data is being tracked.   It could be your CDa collection (CDs, yourcoins, friendsbaseball birthdayscards, orbooks), a diary, an electronic organizer (birthdays/anniversaries/phone numbers/addresses), etc.
 
 
You should track the following details:
* A description of the item. (ege.g., title, name)
* A category or tag (genre, topic, relationship (friend,such family)as “friend” or “family”)
* A date (either the date when the entry was made or some other date that is meaningful, (like the birthday)); (the date may be generated or entered manually)
* Other optional fields
 
<br>
The command should support the following [[Command-line arguments]] to run:
* Add a new entry
Line 19 ⟶ 24:
* Print all entries sorted by a date
 
<br>
The category may be realized as a tag or as structure (making all entries in that category subitems)
The category may be realized as a tag or as structure (by making all entries in that category subitems)
 
The file format on disk should be human readable, but it need not be standardized. &nbsp; A natively available format that doesn't need an external library is preferred. &nbsp; Avoid developing your own format if you can use an already existing one. &nbsp; If there is no existing format available, pick one of:
:::* &nbsp; [[JSON]]
:::* &nbsp; [[S-Expressions]]
:::* &nbsp; [[YAML]]
:::* &nbsp; [[wp:Comparison_of_data_serialization_formats|others]]
 
 
;Related task:
* &nbsp; [[Take notes on the command line]]
<br><br>
 
=={{header|11l}}==
{{trans|Kotlin}}
 
<syntaxhighlight lang="11l">T Item
String name, date, category
 
F (name, date, category)
.name = name
.date = date
.category = category
 
F String()
R .name‘, ’(.date)‘, ’(.category)
 
V db_filename = ‘simdb.csv’
 
F load()
[Item] db
L(line) File(:db_filename).read().rtrim("\n").split("\n")
V item = line.split(‘, ’)
db.append(Item(item[0], item[1], item[2]))
R db
 
F store(item)
File(:db_filename, APPEND).write(String(item)"\n")
 
F printUsage()
print(|‘
Usage:
simdb cmd [categoryName]
add add item, followed by optional category
latest print last added item(s), followed by optional category
all print all
For instance: add "some item name" "some category name’)
 
F addItem(args)
I args.len < 2
printUsage()
R
 
V date = Time().strftime(‘%Y-%m-%d %H:%M:%S’)
V cat = I args.len == 3 {args[2]} E ‘none’
store(Item(args[1], date, cat))
 
F printLatest(a)
V db = load()
I db.empty
print(‘No entries in database.’)
R
 
I a.len == 2
L(item) reversed(db)
I item.category == a[1]
print(item)
L.break
L.was_no_break
print(‘There are no items for category '’a[1]‘'’)
E
print(db.last)
 
F printAll()
V db = load()
I db.empty
print(‘No entries in database.’)
R
 
L(item) db
print(item)
 
:start:
I :argv.len C 2..4
S :argv[1].lowercase()
‘add’
addItem(:argv[1..])
‘latest’
printLatest(:argv[1..])
‘all’
printAll()
E
printUsage()
E
printUsage()</syntaxhighlight>
 
{{out}}
The same as in Kotlin.
 
=={{header|BASIC}}==
==={{header|Applesoft BASIC}}===
This program relies on DOS 3.3 to read and write the simple database as a text file on disk. Running the program with no options displays help on how to run the program with the various options.
<syntaxhighlight lang="gwbasic"> 10 FOR I = 0 TO 255:C = PEEK (512 + I):EOL = C = 0 OR C = 141: IF NOT EOL THEN C$ = C$ + CHR$ (C): NEXT I: STOP
20 DOS = (C = 141) * 128:AC = 0: FOR C = I - 1 TO 0 STEP - 1: IF PEEK (512 + C) = ASC (",") + DOS THEN AC = AC + 1: NEXT C
30 D$ = CHR$ (4):M$ = CHR$ (13): READ P$,C$(1),C$(2),C$(3),C$(4):F$ = P$ + ".TXT": ON AC GOTO 100,40,40,40: GOTO 500USAGE
40 C = 0: PRINT D$"OPEN "F$: PRINT D$"READ "F$
50 ONERR GOTO 80
60 INPUT "";NA$,GE$,DA$
70 C = C + 1: GOTO 60
80 POKE 216,0: IF PEEK (222) = 5 THEN PRINT D$"CLOSE "F$: ON AC GOTO 100,200,300,400
90 RESUME
 
REM ADD
100 PRINT M$C$(AC)M$
110 INPUT " NAME: ";NAME$
120 INPUT " GENRE: ";GENRE$
130 INPUT "DATE YYYY-MM-DD: ";DA$
140 PRINT D$"OPEN "F$: PRINT D$"APPEND "F$: PRINT D$"WRITE "F$: PRINT NAME$","GENRE$","DA$: PRINT D$"CLOSE "F$
150 GOTO 600"DONE
 
REM LATEST
200 PRINT M$C$(AC)M$M$" NAME: "NA$M$"GENRE: "GE$M$" DATE: "DA$;
210 GOTO 600"DONE
 
REM LATEST OF EACH GENRE
300 DIM NA$(C),GE$(C),DA$(C):GC = 0: PRINT D$"OPEN "F$: PRINT D$"READ "F$: FOR I = 1 TO C: GOSUB 350:NA$(J) = NA$:GE$(J) = GE$:DA$(J) = DA$: NEXT I: PRINT D$"CLOSE "F$
310 PRINT M$C$(AC)M$: FOR I = 1 TO GC: PRINT M$NA$(I)","GE$(I)","DA$(I);: NEXT I
320 GOTO 600"DONE
350 INPUT "";NA$,GE$,DA$: FOR J = 1 TO GC: IF GE$ = GE$(J) THEN RETURN
360 NEXT J:GC = GC + 1:J = GC: RETURN
 
REM ALL SORTED BY DATE
400 DIM NA$(C),GE$(C),DA$(C),DA(C):DC = 0: PRINT D$"OPEN "F$: PRINT D$"READ "F$: FOR I = 1 TO C: GOSUB 450:NA$(DC) = NA$:GE$(DC) = GE$:DA$(DC) = DA$:DA(DC) = DA(DP):DA(DP) = DC: NEXT I: PRINT D$"CLOSE "F$
410 PRINT M$C$(AC)M$:DA = DA(0): FOR I = 1 TO DC: PRINT M$NA$(DA)","GE$(DA)","DA$(DA);:DA = DA(DA): NEXT I
420 GOTO 600"DONE
450 DP = 0: INPUT "";NA$,GE$,DA$: IF NOT DC THEN DC = 1: RETURN
460 FOR J = 1 TO DC:DA = DA(DP): IF DA$ > DA$(DA) THEN DP = DA:DA = DA(DA): NEXT J:DA = DP
470 DC = DC + 1: RETURN
 
REM USAGE
500 DATA "SIMPLE DATABASE"
510 DATA " RUN: , ADD A NEW ENTRY"
520 DATA " RUN: ,, PRINT THE LATEST ENTRY"
530 DATA " RUN: ,,, LATEST OF EACH GENRE"
540 DATA " RUN: ,,,, ALL SORTED BY DATE"
550 IF NOT DOS THEN C$ = "RUN " + P$
560 PRINT "USAGE:"M$" "C$" ,..."M$" OR";: FOR I = 1 TO 4: PRINT M$C$(I);: NEXT I
 
REM DONE
600 END</syntaxhighlight>
==={{header|Run BASIC}}===
<syntaxhighlight lang="runbasic">sqliteconnect #sql, "f:\client.db" ' Connect to the DB
 
' -------------------------------
' show user options
' -------------------------------
[sho]
cls ' clear screen
button #acd, "Add a new entry", [add]
button #acd, "Print the latest entry", [last]
button #acd, "Print the latest entry for each category", [lastCat]
button #acd, "Print all entries sorted by a date", [date]
button #ex, "Exit", [exit]
wait
 
' ------------------------------------
' add a new entry (user input screen)
' ------------------------------------
[add]
cls ' clear the screen
html "<TABLE BORDER=1 CELLPADDING=0 CELLSPACING=0 bgcolor=wheat>"
html "<TR align=center BGCOLOR=tan><TD colspan=2>Client Maintenance</TD></TR><TR>"
html "<TD bgcolor=tan align=right>Client Num</TD><TD>"
textbox #clientNum,clientNum$,5
 
html "</TD></TR><TR><TD bgcolor=tan align=right>Name</TD><TD>"
textbox #name,name$,30
 
html "</TD></TR><TR><TD bgcolor=tan align=right>Client Date</TD><TD>"
textbox #clientDate,clientDate$,19
 
html "</TD></TR><TR><TD bgcolor=tan align=right>Category</TD><TD>"
textbox #category,category$,10
 
html "</TD></TR><TR><TR bgcolor=tan><TD colspan=2 ALIGN=CENTER>"
button #acd, "Add", [addIt]
button #ex, "Exit", [sho]
html "</TD></TR></TABLE>"
wait
 
' ---------------------------------------------
' Get data from the screen
' ---------------------------------------------
[addIt]
clientNum = #clientNum contents$()
name$ = trim$(#name contents$())
clientDate$ = trim$(#clientDate contents$())
category$ = trim$(#category contents$())
dbVals$ = clientNum;",'";name$;"','";clientDate$;"','";category$;"'"
sql$ = "INSERT into client VALUES ("; dbVals$ ; ")"
#sql execute(sql$)
goto [sho]
 
' ------------------------------------
' Select last entry
' ------------------------------------
[last]
sql$ = "SELECT *,client.rowid as rowid FROM client ORDER BY rowid desc LIMIT 1"
what$ = "---- Last Entry ----"
goto [shoQuery]
 
' ------------------------------------
' Select by category (Last date only)
' ------------------------------------
[lastCat]
sql$ = "SELECT * FROM client
WHERE client.clientDate = (SELECT max(c.clientDate)
FROM client as c WHERE c.category = client.category)
ORDER BY category"
what$ = "---- Last Category Sequence ----"
goto [shoQuery]
 
' ------------------------------------
' Select by date
' ------------------------------------
[date]
sql$ = "SELECT * FROM client ORDER BY clientDate"
what$ = "---- By Date ----"
 
[shoQuery]
cls
print what$
html "<TABLE BORDER=1 CELLPADDING=0 CELLSPACING=0>"
html "<TR align=center bgcolor=wheat><TD>Client<br>Num</TD><TD>Name</TD><TD>Client<br>Date</TD><TD>Category</TD></TR>" ' heading
#sql execute(sql$)
WHILE #sql hasanswer()
#row = #sql #nextrow()
clientNum = #row clientNum()
name$ = #row name$()
clientDate$ = #row clientDate$()
category$ = #row category$()
 
html "<TR><TD align=right>";clientNum;"</TD><TD>";name$;"</TD><TD>";clientDate$;"</TD><TD>";category$;"</TD></TR>"
WEND
html "</TABLE>"
button #c, "Continue", [sho]
wait
 
' ------ the end -------
[exit]
end</syntaxhighlight>
Output:
 
---- User Input ----<br />
<TABLE BORDER=1 CELLPADDING=0 CELLSPACING=0 bgcolor=wheat>
<TR align=center BGCOLOR=tan><TD colspan=2>Client Maintenance</TD></TR>
<TR><TD bgcolor=tan align=right>Client Num</TD><TD>5</TD></TR>
<TR><TD bgcolor=tan align=right>Name</TD><TD>Dawnridge Winery</TD></TR>
<TR><TD bgcolor=tan align=right>Client Date</TD><TD>2008-06-18 22:16</TD></TR>
<TR><TD bgcolor=tan align=right>Category</TD><TD>wine</TD></TR>
<TR><TR bgcolor=tan><TD colspan=2 ALIGN=CENTER>[Add] [Exit]</TD></TR></TABLE>
 
---- Last Entry ----<br />
<TABLE BORDER=1 CELLPADDING=0 CELLSPACING=0>
<TR align=center bgcolor=wheat><TD>Client<br>Num</TD><TD>Name</TD><TD>Client<br>Date</TD><TD>Category</TD></TR>
<TR><TD align=right>5</TD><TD>Dawnridge Winery</TD><TD>2008-06-18 22:16</TD><TD>wine</TD></TR></TABLE>
 
---- Last category Sequence ----<br />
<TABLE BORDER=1 CELLPADDING=0 CELLSPACING=0>
<TR align=center bgcolor=wheat><TD>Client<br>Num</TD><TD>Name</TD><TD>Client<br>Date</TD><TD>Category</TD></TR>
<TR><TD align=right>1</TD><TD>Home Sales</TD><TD>2012-01-01 10;20</TD><TD>broker</TD></TR>
<TR><TD align=right>4</TD><TD>Back 40 Equipment</TD><TD>2009-09-18 20:18</TD><TD>farm</TD></TR>
<TR><TD align=right>3</TD><TD>Floral Designs</TD><TD>2010-10-14 09:16</TD><TD>flowers</TD></TR>
<TR><TD align=right>2</TD><TD>Best Foods</TD><TD>2011-02-02 12:33</TD><TD>food</TD></TR>
<TR><TD align=right>5</TD><TD>Dawnridge Winery</TD><TD>2008-06-18 22:16</TD><TD>wine</TD></TR></TABLE>
 
---- Date Sequence ----<br />
<TABLE BORDER=1 CELLPADDING=0 CELLSPACING=0>
<TR align=center bgcolor=wheat><TD>Client<br>Num</TD><TD>Name</TD><TD>Client<br>Date</TD><TD>Category</TD></TR>
<TR><TD align=right>5</TD><TD>Dawnridge Winery</TD><TD>2008-06-18 22;16</TD><TD>wine</TD></TR>
<TR><TD align=right>4</TD><TD>Back 40 Equipment</TD><TD>2009-09-18 20:18</TD><TD>farm</TD></TR>
<TR><TD align=right>3</TD><TD>Floral Designs</TD><TD>2010-10-14 09:16</TD><TD>flowers</TD></TR>
<TR><TD align=right>2</TD><TD>Best Foods</TD><TD>2011-02-02 12:33</TD><TD>food</TD></TR>
<TR><TD align=right>1</TD><TD>Home Sales</TD><TD>2012-01-01 10:20</TD><TD>broker</TD></TR></TABLE>
 
=={{header|Bracmat}}==
This is a rather minimal solution. The program is run from the command line of the operating system, in this example the Windows command prompt. The program is stored in a file called 'sdb':
<syntaxhighlight lang="bracmat"> whl
' ( arg$:?command
& ( get'db
| (db=1)&lst$(db,db,NEW)
)
& !command
: ( add
& :?name:?tag:?date
& whl
' ( arg$:?argmnt
& arg$:?value
& (!argmnt.!value)
: ( (title|name.?name)
| (category|tag.?tag)
| (date.?date)
)
)
& ( !name:~
& !tag:~
& !date:~
& ( !db:?*!tag^(?+(!date.!name)+?)*?
& out$"This record already exists"
| !tag^(!date.!name)*!db:?db
& lst$(db,db,NEW)
)
| out$"invalid data"
)
| latest
& :?date
& nothing found:?latest
& ( !db
: ?
* ?tag
^ ( ?
+ ( (>!date:?date.?name)
& (!name,!tag,!date):?latest
& ~
)
+ ?
)
* ?
| out$!latest
)
| latest/category
& :?date:?latests:?latest
& ( !db
: ?
* ( ?tag
& !latests !latest:?latests
& :?latest:?date
)
^ ( ?
+ ( (>!date:?date.?name)
& (!name,!tag,!date):?latest
& ~
)
+ ?
)
* ?
| !latests !latest:?latests&out$!latests
)
| sorted
& 0:?sorted
& ( !db
: ?
* ?tag
^ ( ?
+ ( (?date.?name)
& (!date.!name,!tag,!date)+!sorted:?sorted
& ~
)
+ ?
)
* ?
| whl
' (!sorted:(?.?row)+?sorted&out$!row)
)
)
);
</syntaxhighlight>
First we add some records, a some ships that arrived at the harbour in Rotterdam today.
<pre>bracmat "get$sdb" add name "CORONA BULKER" tag "BULK CARRIER" date "2014.10.21.04:00"
bracmat "get$sdb" add name "FPMC 21" tag "CHEMICAL TANKER" date "2014.10.15.12:00"
bracmat "get$sdb" add name "CHINA PROGRESS" tag "BULK CARRIER" date "2014.10.13.22:00"
bracmat "get$sdb" add name "FAIRCHEM YUKA" tag "CHEMICAL TANKER" date "2014.10.13.12:00"
bracmat "get$sdb" add name "NAVE COSMOS" tag "CHEMICAL TANKER" date "2014.10.13.10:00"
bracmat "get$sdb" add name "GOLDEN ICE" tag "BULK CARRIER" date "2014.10.10.12:00"
bracmat "get$sdb" add name "GHAZAL" tag "CRUDE OIL" date "2014.10.10.12:00"
bracmat "get$sdb" add name "HS MEDEA" tag "CRUDE OIL" date "2014.10.10.02:00"</pre>
Instead of 'name' you can use 'title' and instead of 'tag' you can use 'category'. The date has to be year first and day last, followed by time information if you like. No attempt is made to validate the date/time. Now the queries:
<pre>prompt> bracmat "get$sdb" latest
CORONA BULKER,BULK CARRIER,2014.10.21.04:00
 
prompt> bracmat "get$sdb" latest/category
(CORONA BULKER,BULK CARRIER,2014.10.21.04:00)
(FPMC 21,CHEMICAL TANKER,2014.10.15.12:00)
(GHAZAL,CRUDE OIL,2014.10.10.12:00)
 
prompt> bracmat "get$sdb" sorted
HS MEDEA,CRUDE OIL,2014.10.10.02:00
GHAZAL,CRUDE OIL,2014.10.10.12:00
GOLDEN ICE,BULK CARRIER,2014.10.10.12:00
NAVE COSMOS,CHEMICAL TANKER,2014.10.13.10:00
FAIRCHEM YUKA,CHEMICAL TANKER,2014.10.13.12:00
CHINA PROGRESS,BULK CARRIER,2014.10.13.22:00
FPMC 21,CHEMICAL TANKER,2014.10.15.12:00
CORONA BULKER,BULK CARRIER,2014.10.21.04:00</pre>
 
The database file 'db' looks like this:
<pre>db= "BULK CARRIER"
^ ( ("2014.10.10.12:00"."GOLDEN ICE")
+ ("2014.10.13.22:00"."CHINA PROGRESS")
+ ("2014.10.21.04:00"."CORONA BULKER")
)
* "CHEMICAL TANKER"
^ ( ("2014.10.13.10:00"."NAVE COSMOS")
+ ("2014.10.13.12:00"."FAIRCHEM YUKA")
+ ("2014.10.15.12:00"."FPMC 21")
)
* "CRUDE OIL"^(("2014.10.10.02:00"."HS MEDEA")+("2014.10.10.12:00".GHAZAL));</pre>
 
Use is made of Bracmat's automatic normalization of algebraic formula to turn the data into a hierarchical structure, with the tag as the top level and the date/time immediately below that level.
 
=={{header|C}}==
A simple database in C with some error checking, even. A quick test with Valgrind revealed no obvious memory leaks. The following data was used for testing. -> database.csv
 
"Soon Rising","Dee","Lesace","10-12-2000","New Hat Press"
"Brave Chicken","Tang","Owe","04-01-2008","Nowhere Press"
"Aardvark Point","Dee","Lesace","5-24-2001","New Hat Press"
"Bat Whisperer, The","Tang","Owe","01-03-2004","Nowhere Press"
"Treasure Beach","Argus","Jemky","09-22-1999","Lancast"
 
<syntaxhighlight lang="c">#include <stdio.h>
#include <stdlib.h> /* malloc */
#include <string.h> /* strlen */
#define _XOPEN_SOURCE /* requred for time functions */
#define __USE_XOPEN
#include <time.h>
#define DB "database.csv" /* database name */
#define TRY(a) if (!(a)) {perror(#a);exit(1);}
#define TRY2(a) if((a)<0) {perror(#a);exit(1);}
#define FREE(a) if(a) {free(a);a=NULL;}
#define sort_by(foo) \
static int by_##foo (const void*p1, const void*p2) { \
return strcmp ((*(const pdb_t*)p1)->foo, (*(const pdb_t*)p2)->foo); }
typedef struct db {
char title[26];
char first_name[26];
char last_name[26];
time_t date;
char publ[100];
struct db *next;
}
db_t,*pdb_t;
typedef int (sort)(const void*, const void*);
enum {CREATE,PRINT,TITLE,DATE,AUTH,READLINE,READ,SORT,DESTROY};
static pdb_t dao (int cmd, FILE *f, pdb_t db, sort sortby);
static char *time2str (time_t *time);
static time_t str2time (char *date);
/* qsort callbacks */
sort_by(last_name);
sort_by(title);
static int by_date(pdb_t *p1, pdb_t *p2);
/* main */
int main (int argc, char **argv) {
char buf[100];
const char *commands[]={"-c", "-p", "-t", "-d", "-a", NULL};
db_t db;
db.next=NULL;
pdb_t dblist;
int i;
FILE *f;
TRY (f=fopen(DB,"a+"));
if (argc<2) {
usage: printf ("Usage: %s [commands]\n"
"-c Create new entry.\n"
"-p Print the latest entry.\n"
"-t Print all entries sorted by title.\n"
"-d Print all entries sorted by date.\n"
"-a Print all entries sorted by author.\n",argv[0]);
fclose (f);
return 0;
}
for (i=0;commands[i]&&strcmp(argv[1],commands[i]);i++);
switch (i) {
case CREATE:
printf("-c Create a new entry.\n");
printf("Title :");if((scanf(" %25[^\n]",db.title ))<0)break;
printf("Author Firstname:");if((scanf(" %25[^\n]",db.first_name))<0)break;
printf("Author Lastname :");if((scanf(" %25[^\n]",db.last_name ))<0)break;
printf("Date 10-12-2000 :");if((scanf(" %10[^\n]",buf ))<0)break;
printf("Publication :");if((scanf(" %99[^\n]",db.publ ))<0)break;
db.date=str2time (buf);
dao (CREATE,f,&db,NULL);
break;
case PRINT:
printf ("-p Print the latest entry.\n");
while (!feof(f)) dao (READLINE,f,&db,NULL);
dao (PRINT,f,&db,NULL);
break;
case TITLE:
printf ("-t Print all entries sorted by title.\n");
dblist = dao (READ,f,&db,NULL);
dblist = dao (SORT,f,dblist,by_title);
dao (PRINT,f,dblist,NULL);
dao (DESTROY,f,dblist,NULL);
break;
case DATE:
printf ("-d Print all entries sorted by date.\n");
dblist = dao (READ,f,&db,NULL);
dblist = dao (SORT,f,dblist,(int (*)(const void *,const void *)) by_date);
dao (PRINT,f,dblist,NULL);
dao (DESTROY,f,dblist,NULL);
break;
case AUTH:
printf ("-a Print all entries sorted by author.\n");
dblist = dao (READ,f,&db,NULL);
dblist = dao (SORT,f,dblist,by_last_name);
dao (PRINT,f,dblist,NULL);
dao (DESTROY,f,dblist,NULL);
break;
default: {
printf ("Unknown command: %s.\n",strlen(argv[1])<10?argv[1]:"");
goto usage;
} }
fclose (f);
return 0;
}
/* Data Access Object (DAO) */
static pdb_t dao (int cmd, FILE *f, pdb_t in_db, sort sortby) {
pdb_t *pdb=NULL,rec=NULL,hd=NULL;
int i=0,ret;
char buf[100];
switch (cmd) {
case CREATE:
fprintf (f,"\"%s\",",in_db->title);
fprintf (f,"\"%s\",",in_db->first_name);
fprintf (f,"\"%s\",",in_db->last_name);
fprintf (f,"\"%s\",",time2str(&in_db->date));
fprintf (f,"\"%s\" \n",in_db->publ);
break;
case PRINT:
for (;in_db;i++) {
printf ("Title : %s\n", in_db->title);
printf ("Author : %s %s\n", in_db->first_name, in_db->last_name);
printf ("Date : %s\n", time2str(&in_db->date));
printf ("Publication : %s\n\n", in_db->publ);
if (!((i+1)%3)) {
printf ("Press Enter to continue.\n");
ret = scanf ("%*[^\n]");
if (ret<0) return rec; /* handle EOF */
else getchar();
}
in_db=in_db->next;
}
break;
case READLINE:
if((fscanf(f," \"%[^\"]\",",in_db->title ))<0)break;
if((fscanf(f," \"%[^\"]\",",in_db->first_name))<0)break;
if((fscanf(f," \"%[^\"]\",",in_db->last_name ))<0)break;
if((fscanf(f," \"%[^\"]\",",buf ))<0)break;
if((fscanf(f," \"%[^\"]\" ",in_db->publ ))<0)break;
in_db->date=str2time (buf);
break;
case READ:
while (!feof(f)) {
dao (READLINE,f,in_db,NULL);
TRY (rec=malloc(sizeof(db_t)));
*rec=*in_db; /* copy contents */
rec->next=hd;/* to linked list */
hd=rec;i++;
}
if (i<2) {
puts ("Empty database. Please create some entries.");
fclose (f);
exit (0);
}
break;
case SORT:
rec=in_db;
for (;in_db;i++) in_db=in_db->next;
TRY (pdb=malloc(i*sizeof(pdb_t)));
in_db=rec;
for (i=0;in_db;i++) {
pdb[i]=in_db;
in_db=in_db->next;
}
qsort (pdb,i,sizeof in_db,sortby);
pdb[i-1]->next=NULL;
for (i=i-1;i;i--) {
pdb[i-1]->next=pdb[i];
}
rec=pdb[0];
FREE (pdb);
pdb=NULL;
break;
case DESTROY: {
while ((rec=in_db)) {
in_db=in_db->next;
FREE (rec);
} } }
return rec;
}
/* convert numeric time to date string */
static char *time2str (time_t *time) {
static char buf[255];
struct tm *ptm;
ptm=localtime (time);
strftime(buf, 255, "%m-%d-%Y", ptm);
return buf;
}
/* convert date string to numeric time */
static time_t str2time (char *date) {
struct tm tm;
memset (&tm, 0, sizeof(struct tm));
strptime(date, "%m-%d-%Y", &tm);
return mktime(&tm);
}
/* sort by date callback for qsort */
static int by_date (pdb_t *p1, pdb_t *p2) {
if ((*p1)->date < (*p2)->date) {
return -1;
}
else return ((*p1)->date > (*p2)->date);
}</syntaxhighlight>
 
=={{header|C sharp|C#}}==
<syntaxhighlight lang="c sharp">
using System;
using System.IO;
 
namespace Simple_database
{
class Program
{
public static void Main(string[] args)
{
//
// For appropriate use of this program
// use standard Windows Command Processor or cmd.exe
//
// Create cmd.bat file at the same folder with executive version
// of program Simple_database.exe, so when started, the correct
// file path will be automatically set to cmd console.
//
// Start notepad, write only cmd.exe and save file as cmd.bat
//
// To start cmd just double click at cmd.bat file.
//
//
//
// Console application command line start command
//
// application name.exe [argument] [argument parameters]
//
//
// Command line argument followed by parameters
//
// [a] - Add new entry
//
// ["data1"]["data2"]["data3"]...["data n"]
//
// ["data1"] - Data category !
// ["data2"] - Data
// ["data3"] - Data
//
//
// NOTICE !
//
// First parameter is taken for data category.
//
//
//
// Command line argument with no parameters
//
// [p1] - Print the latest entry
//
// [p2] - Print the latest entry for each category
//
// [p3] - Print all entries sorted by a date
//
//
//
//
// Command line example
//
// Small_database.exe [a] ["home"] ["+398125465458"] ["My tel number"]
//
// Small_database.exe [a] ["office"] ["+398222789000"] ["Boss"]
//
// Small_database.exe [a] [cd] ["Action movie"] ["Movie title"]
// Small_database.exe [a] [cd] ["SF movie"] ["Movie title"]
// Small_database.exe [a] [dvd] ["Action movie"] ["Movie title"]
//
//
// NOTICE !
//
// Brackets and space between arguments and parameters are necessary.
// Quotes must be used when parameters have more than one word.
//
// If not used as shown in examples, program will show error message.
//
//
//
// Check command line for arguments
//
//
if(args.Length==0)
{
Console.WriteLine();
Console.WriteLine(" Missing Argument Error. ");
Console.WriteLine();
}
else
{
switch (args[0])
{
case "[a]" : Add_New_Entry(args);
break;
case "[p1]": Print_Document("Print the latest entry.txt");
break;
case "[p2]": Print_Document("Print the latest entry for each category.txt");
break;
case "[p3]": Print_Document("Print all entries sorted by a date.txt");
break;
default :
{
Console.WriteLine();
Console.WriteLine(" Incorrect Argument Error. ");
Console.WriteLine();
}
break;
}
}
}
static void Add_New_Entry(string [] args)
{
//
// Check parameters
//
//
// Minimum one parameter, category
//
if(args.Length==1)
{
Console.WriteLine();
Console.WriteLine(" Missing Parameters Error..... ");
Console.WriteLine();
}
else
{
bool parameters_ok = true;
foreach (string a in args)
{
if(!a.StartsWith("[") || !a.EndsWith("]"))
{
parameters_ok = !parameters_ok;
break;
}
}
//
// Add new entry to Data base document
//
if(parameters_ok)
{
//
//
//
Console.WriteLine();
Console.WriteLine(" Parameters are ok..... ");
Console.WriteLine();
Console.WriteLine(" Writing new entry to database..... ");
//
// Create new Data base entry
//
args[0] = string.Empty;
string line = string.Empty;
foreach (string a in args)
{
line+=a;
}
line+="[" + DateTime.Now.ToString() + "]";
args[0] = "[" + DateTime.Now.ToString() + "]";
//
// Write entry to Data base
//
StreamWriter w = new StreamWriter("Data base.txt",true);
w.WriteLine(line);
//
// Close and dispose stream writer
//
w.Close();
w.Dispose();
//
//
//
Console.WriteLine();
Console.WriteLine(" New entry is written to database. ");
 
Create_Print_Documents(args);
//
//
//
Console.WriteLine();
Console.WriteLine(" Add new entry command executed. ");
//
//
//
}
else
{
Console.WriteLine();
Console.WriteLine(" ! Parameters are not ok ! ");
Console.WriteLine();
Console.WriteLine(" Add new entry command is not executed. ");
Console.WriteLine();
}
}
}
static void Create_Print_Documents(string [] args)
{
//
//
//
Console.WriteLine();
Console.WriteLine(" Creating new print documents. ");
//
// Create "Print all entries sorted by a date.txt"
//
File.Copy("Data base.txt","Print all entries sorted by a date.txt",true);
//
//
//
Console.WriteLine();
Console.WriteLine(" Print all entries sorted by a date.txt created. ");
//
// Create "Print the latest entry.txt"
//
//
// Create new entry
//
string line = string.Empty;
foreach (string a in args)
{
line+=a;
}
//
StreamWriter w = new StreamWriter("Print the latest entry.txt");
//
w.WriteLine(line);
//
w.Close();
w.Dispose();
//
//
//
Console.WriteLine();
Console.WriteLine(" Print the latest entry.txt created. ");
//
// Create "Print the latest entry for each category.txt"
//
string latest_entry = string.Empty;
foreach (string a in args)
{
latest_entry+=a;
}
if(!File.Exists("Print the latest entry for each category.txt"))
{
File.WriteAllText("Print the latest entry for each category.txt",latest_entry);
}
else
{
StreamReader r = new StreamReader("Print the latest entry for each category.txt");
//
w = new StreamWriter("Print the latest entry for each category 1.txt",true);
//
line = string.Empty;
//
while(!r.EndOfStream)
{
line = r.ReadLine();
if(line.Contains(args[1].ToString()))
{
w.WriteLine(latest_entry);
latest_entry = "ok";
}
else
{
w.WriteLine(line);
}
}
// add new category
if(latest_entry != "ok")
w.WriteLine(latest_entry);
//
w.Close();
w.Dispose();
//
r.Close();
r.Dispose();
//
File.Copy("Print the latest entry for each category 1.txt",
"Print the latest entry for each category.txt",true);
//
File.Delete("Print the latest entry for each category 1.txt");
//
//
//
Console.WriteLine();
Console.WriteLine(" Print the latest entry for each category.txt created. ");
Console.WriteLine();
}
}
static void Print_Document(string file_name)
{
//
// Print document
//
Console.WriteLine();
Console.WriteLine(file_name.Replace(".txt","")+ " : ");
Console.WriteLine();
//
StreamReader r = new StreamReader(file_name);
//
string line = string.Empty;
//
line = r.ReadToEnd();
//
Console.WriteLine(line);
//
r.Close();
r.Dispose();
//
//
//
}
}
}
</syntaxhighlight>
{{out| Program Input and Output}}
<pre>
Data base can be filled by creating cmd.bat file with following contents:
</pre>
<pre>
Simple_database.exe [a] [cd] ["Action"] ["Movie name"]
Simple_database.exe [a] [cd] ["Fiction"] ["Movie name"]
Simple_database.exe [a] [cd] ["Drama"] ["Movie name"]
Simple_database.exe [a] [cd] ["SF"] ["Movie name"]
Simple_database.exe [a] [cd] ["Comedy"] ["Movie name"]
Simple_database.exe [a] [cd] ["Horor"] ["Movie name"]
 
Simple_database.exe [a] [dvd] ["Action"] ["Movie name"] ["Fiction"] ["Movie name"]
Simple_database.exe [a] [dvd] ["SF"] ["Movie name"] ["SF"] ["Movie name"]
Simple_database.exe [a] [dvd] ["Drama"] ["Movie name"] ["Action"] ["Movie name"]
Simple_database.exe [a] [dvd] ["Comedy"] ["Movie name"] ["SF"] ["Movie name"]
Simple_database.exe [a] [dvd] ["Horor"] ["Movie name"] ["Fiction"] ["Movie name"]
 
pause
</pre>
<pre>
When data base is formed use start command with parameters for data base query:
 
C:\PROJECTS\Roseta\Simple database\Simple database\bin\Debug>Simple_database.exe [p2]
 
And the result is
</pre>
<pre>
Print the latest entry for each category :
 
[28.3.2018 15:06:18][cd][Horor][Movie name]
[28.3.2018 15:06:18][dvd][Horor][Movie name][Fiction][Movie name]
</pre>
 
=={{header|COBOL}}==
This is a souped-up version of the task from [[Take notes on the command line]]. It stores the current date, a tag, a title and a note as an entry in a file. The database produced is not particularly human-readable or easy to modify, but it is in a well-structured format.
{{works with|OpenCOBOL}}
<syntaxhighlight lang="cobol"> IDENTIFICATION DIVISION.
PROGRAM-ID. simple-database.
 
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
SELECT OPTIONAL database-file ASSIGN Database-Path
ORGANIZATION INDEXED
ACCESS SEQUENTIAL
RECORD KEY data-title
ALTERNATE RECORD KEY data-tag
WITH DUPLICATES
ALTERNATE RECORD KEY date-added
WITH DUPLICATES
FILE STATUS file-status
.
DATA DIVISION.
FILE SECTION.
FD database-file.
01 database-record.
*> Date is in YYYYMMDD format.
03 date-added PIC 9(8).
03 data-tag PIC X(20).
03 data-title PIC X(50).
03 data-contents PIC X(200).
*> Adding extra space is considered good style so the record
*> can be expanded in the future.
03 FILLER PIC X(50).
 
WORKING-STORAGE SECTION.
78 Database-Path VALUE "database.dat".
 
01 file-status PIC XX.
88 file-ok VALUE "00".
88 duplicate-key VALUE "22".
88 key-not-found VALUE "23".
 
01 num-args PIC 99.
 
01 action PIC XX.
88 create-entry VALUE "-c".
88 remove-entry VALUE "-r".
88 find-entry VALUE "-f".
88 print-latest VALUE "-l".
88 print-database VALUES "-a", "-d", "-t".
*> Printed by title.
88 print-by-title VALUE "-a".
88 print-by-date VALUE "-d".
88 print-by-tag VALUE "-t".
88 print-help VALUES "-h", SPACES.
 
01 read-direction-flag PIC X VALUE SPACE.
88 read-backwards VALUE "B".
 
01 edited-date PIC 9(4)/99/99.
PROCEDURE DIVISION.
DECLARATIVES.
database-file-error SECTION.
USE AFTER ERROR ON database-file
 
DISPLAY "An error has occurred while using " Database-Path
". Error no. " file-status
DISPLAY "The program will terminate."
 
CLOSE database-file
 
GOBACK
.
END DECLARATIVES.
 
main-line.
DISPLAY 1 UPON ARGUMENT-NUMBER
ACCEPT action FROM ARGUMENT-VALUE
 
ACCEPT num-args FROM ARGUMENT-NUMBER
 
EVALUATE TRUE
WHEN create-entry
IF num-args >= 4
PERFORM write-entry
ELSE
DISPLAY "-a requires arguments to enter in the "
"database. See help (-h) for details."
END-IF
 
WHEN remove-entry
IF num-args >= 2
PERFORM delete-entry
ELSE
DISPLAY "-r requires the title of the entry to "
"delete."
END-IF
 
WHEN find-entry
IF num-args >= 2
PERFORM display-specified-entry
ELSE
DISPLAY "-f requires the title of the entry to "
"find."
END-IF
 
WHEN print-latest
PERFORM show-latest
 
WHEN print-database
PERFORM show-database
 
WHEN print-help
PERFORM show-general-help
 
WHEN OTHER
DISPLAY action " is not a valid option."
END-EVALUATE
GOBACK
.
write-entry.
OPEN EXTEND database-file
 
DISPLAY 2 UPON ARGUMENT-NUMBER
ACCEPT data-tag FROM ARGUMENT-VALUE
DISPLAY 3 UPON ARGUMENT-NUMBER
ACCEPT data-title FROM ARGUMENT-VALUE
IF data-title = SPACES
DISPLAY "The title cannot be blank."
PERFORM close-and-terminate
END-IF
 
DISPLAY 4 UPON ARGUMENT-NUMBER
ACCEPT data-contents FROM ARGUMENT-VALUE
 
ACCEPT date-added FROM DATE YYYYMMDD
 
WRITE database-record
INVALID KEY
IF duplicate-key
DISPLAY "An entry in the database already has "
"that title. Please choose a different "
"title or remove the entry."
ELSE
PERFORM database-file-error
END-IF
END-WRITE
 
PERFORM close-database
.
delete-entry.
PERFORM get-title-arg
OPEN I-O database-file
PERFORM read-title
 
DELETE database-file
 
PERFORM close-database
.
display-specified-entry.
PERFORM get-title-arg
OPEN INPUT database-file
PERFORM read-title
 
PERFORM show-record
 
PERFORM close-database
.
get-title-arg.
DISPLAY 2 UPON ARGUMENT-NUMBER
ACCEPT data-title FROM ARGUMENT-VALUE
.
read-title.
START database-file KEY IS = data-title
INVALID KEY
IF key-not-found
DISPLAY "An entry with that title was not found."
PERFORM close-and-terminate
ELSE
PERFORM database-file-error
END-IF
END-START
 
READ database-file
.
close-and-terminate.
PERFORM close-database
GOBACK
.
show-latest.
OPEN INPUT database-file
 
PERFORM start-at-last-date
READ database-file
PERFORM show-record
 
PERFORM close-database
.
show-database.
OPEN INPUT database-file
 
EVALUATE TRUE
WHEN print-by-title
*> Primary key is the title.
CONTINUE
WHEN print-by-tag
MOVE LOW-VALUES TO data-tag
START database-file KEY IS > data-tag
WHEN print-by-date
PERFORM start-at-last-date
SET read-backwards TO TRUE
END-EVALUATE
 
PERFORM FOREVER
*> The problem with statements instead of functions...
IF NOT read-backwards
READ database-file NEXT
AT END
EXIT PERFORM
END-READ
ELSE
READ database-file PREVIOUS
AT END
EXIT PERFORM
END-READ
END-IF
 
PERFORM show-record
DISPLAY SPACE
END-PERFORM
 
PERFORM close-database
.
start-at-last-date.
MOVE HIGH-VALUES TO date-added
START database-file KEY IS < date-added
.
close-database.
CLOSE database-file
.
show-record.
MOVE date-added TO edited-date
DISPLAY "Date added: " edited-date " Tag: " data-tag
DISPLAY "Title: " data-title
DISPLAY "Contents:"
DISPLAY " " FUNCTION TRIM(data-contents)
.
show-general-help.
DISPLAY "Help: Possible options are:"
DISPLAY " -a - Show all the entries (sorted by title)."
DISPLAY " -c - Create a new entry in the database. -c needs"
" further arguments in this format:"
DISPLAY ' "tag" "title" "content"'
DISPLAY " Max argument sizes (in characters): tag - 20, "
"title - 50, content - 200"
DISPLAY " The title must be unique and not be blank."
DISPLAY " -d - Show all the entries sorted by date added."
DISPLAY " -f - Finds and displays entry with the title "
"provided. The title should be specified as shown for "
"-c."
DISPLAY " -h - Show this help menu."
DISPLAY " -l - Show the latest entry."
DISPLAY " -r - Remove the entry with the title provided. "
"The title should be specified as shown for -c."
DISPLAY " -t - Show all the entries sorted by tag."
.</syntaxhighlight>
 
Sample session:
<pre>
$ ./database -c "Reminder" "Bob's Birthday" "Buy birthday present for Bob."
$ ./database -c "Wishlist" "Beethoven" "Beethoven's Ode to Joy"
$ ./database -c "Reminder" "Add to Simple Database" "Add brainf*** example for Simple Database on Rosetta Code."
...
$ ./database -f "Mozart"
An entry with that title was not found.
$ ./database -t
Date added: 2013/08/13 Tag: Reminder
Title: Bob's Birthday
Contents:
Buy birthday present for Bob.
Date added: 2013/08/13 Tag: Reminder
Title: Add to Simple Database
Contents:
Add brainf*** example for Simple Database on Rosetta Code.
Date added: 2013/08/13 Tag: Wishlist
Title: Beethoven
Contents:
Beethoven's Ode to Joy
 
$ ./database -r "Beethoven"
$ ./database -l
Date added: 2013/08/13 Tag: Reminder
Title: Add to Simple Database
Contents:
Add brainf*** example for Simple Database on Rosetta Code.
$
</pre>
 
=={{header|Common Lisp}}==
 
Tested with [[Common Lisp]]. ''(Save the code below as db.lisp)''
 
<syntaxhighlight lang="lisp">(defvar *db* nil)
 
(defvar *db-cat* (make-hash-table :test 'equal))
 
(defvar *db-file* "db.txt")
 
(defstruct item
"this is the unit of data stored/displayed in *db*"
(title " ")
(category "default")
(date (progn (get-universal-time))))
 
(defun set-category(new-item)
(setf (gethash (item-category new-item) *db-cat*) 't))
 
(defun find-item-in-db (&optional category)
(if (null category)
(car *db*)
(find category *db* :key #'item-category :test #'string=)))
 
(defun scan-category ()
"scan categories from an existing database -- after reading it from disk"
(dolist (itm *db*) (set-category itm)))
 
(defun pr-univ-time (utime)
(multiple-value-bind
(second minute hour date month year day-of-week dst-p tz)
(decode-universal-time utime)
(declare (ignore day-of-week dst-p tz))
(format nil "~4,'0d-~2,'0d-~2,'0d ~2,'0d:~2,'0d:~2,'0d" year month date hour minute second)))
 
(defun pr (&optional (item (find-item-in-db)) (stream t))
"print an item"
(when item
(format stream "~a: (~a) (~a)~%"
(item-title item)
(item-category item)
(pr-univ-time (item-date item)))))
 
(defun pr-per-category ()
"print the latest item from each category"
(loop for k being the hash-keys in *db-cat*
do (pr (find-item-in-db k))))
 
(defun pr-all ()
"print all the items, *db* is sorted by time."
(dolist (itm *db*) (pr itm)))
 
(defun pr-all-categories (&optional (stream t))
(loop for k being the hash-keys in *db-cat*
do (format stream "(~a) " k)))
(defun insert-item (item)
"insert item into database in a time sorted list. okay for a small list, as per spec."
(let ((first-item (car *db*)) (new-itm item))
(set-category new-itm)
(push new-itm *db*)
(when (and first-item (>= (item-date new-itm) (item-date first-item)))
(setf *db* (sort *db* #'> :key #'item-date)))
*db*))
 
(defun read-db-from-file (&optional (file *db-file*))
(with-open-file (in file :if-does-not-exist nil)
(when in
(with-standard-io-syntax (setf *db* (read in)))
(scan-category))))
 
(defun save-db-to-file (&optional (file *db-file*))
(with-open-file (out file :direction :output :if-exists :supersede)
(with-standard-io-syntax
(print *db* out))))
 
(defun del-db ()
(setf *db* nil)
(save-db-to-file))
 
(defun del-item (itm)
(read-db-from-file)
(setf *db* (remove itm *db* :key #'item-title :test #'string=))
(save-db-to-file))
 
(defun add-item-to-db (args)
(read-db-from-file)
(insert-item (make-item :title (first args) :category (second args)))
(save-db-to-file))
 
(defun help-menu ()
(format t "clisp db.lisp ~{~15T~a~^~% ~}"
'("delete <item-name> ------------------- delete an item"
"delete-all --------------------------- delete the database"
"insert <item-name> <item-category> --- insert an item with its category"
"show --------------------------------- shows the latest inserted item"
"show-categories ---------------------- show all categories"
"show-all ----------------------------- show all items"
"show-per-category -------------------- show the latest item per category")))
 
(defun db-cmd-run (args)
(cond ((and (> (length args) 1) (equal (first args) "delete"))
(del-item (second args)))
((equal (first args) "delete-all") (del-db))
((and (> (length args) 2) (equal (first args) "insert"))
(add-item-to-db (rest args)))
((equal (first args) "show") (read-db-from-file) (pr))
((equal (first args) "show-categories") (read-db-from-file) (pr-all-categories))
((equal (first args) "show-all") (read-db-from-file) (pr-all))
((equal (first args) "show-per-category") (read-db-from-file) (pr-per-category))
(t (help-menu))))
 
;; modified https://rosettacode.org/wiki/Command-line_arguments#Common_Lisp
(defun db-argv ()
(or
#+clisp ext:*args*
#+sbcl (cdr sb-ext:*posix-argv*)
#+allegro (cdr (sys:command-line-arguments))
#+lispworks (cdr sys:*line-arguments-list*)
nil))
 
(db-cmd-run (db-argv))</syntaxhighlight>
 
 
Help menu:
$ clisp db.lisp
clisp db.lisp delete <item-name> ------------------- delete an item
delete-all --------------------------- delete the database
insert <item-name> <item-category> --- insert an item with its category
show --------------------------------- shows the latest inserted item
show-categories ---------------------- show all categories
show-all ----------------------------- show all items
show-per-category -------------------- show the latest item per category
 
Here are a few steps to add a few titles, and their categories:
$ clisp db.lisp insert "title-vinyl-1" "vinyl"
$ clisp db.lisp insert "title-cd-1" "cd"
$ clisp db.lisp insert "title-dvd-1" "dvd"
$ clisp db.lisp insert "title-tape-1" "tape"
$ clisp db.lisp insert "title-tape-2" "tape"
 
Here is the very latest entry in the db:
$ clisp db.lisp show
title-tape-2: (tape) (2017-04-04 20:19:06)
 
Here is a (sorted time wise) list of all the entries:
$ clisp db.lisp show-all
title-tape-2: (tape) (2017-04-04 20:19:06)
title-tape-1: (tape) (2017-04-04 20:19:00)
title-dvd-1: (dvd) (2017-04-04 20:18:55)
title-cd-1: (cd) (2017-04-04 20:18:48)
title-vinyl-1: (vinyl) (2017-04-04 20:18:41)
 
Here is the latest entry for each category:
$ clisp db.lisp show-per-category
title-vinyl-1: (vinyl) (2017-04-04 20:18:41)
title-cd-1: (cd) (2017-04-04 20:18:48)
title-dvd-1: (dvd) (2017-04-04 20:18:55)
title-tape-2: (tape) (2017-04-04 20:19:06)
 
Here is the list of all categories:
$ clisp db.lisp show-categories
(vinyl) (cd) (dvd) (tape)
 
To delete an entry:
$ clisp db.lisp delete "title-tape-2"
 
To delete all entries:
$ clisp db.lisp delete-all
 
=={{header|D}}==
<syntaxhighlight lang="d">import std.stdio, std.algorithm, std.string, std.conv, std.array,
std.file, std.csv, std.datetime;
 
private {
immutable filename = "simdb.csv";
 
struct Item {
string name, date, category;
}
 
void addItem(in string[] item) {
if (item.length < 3)
return printUsage();
auto db = load();
const date = (cast(DateTime)Clock.currTime).toISOExtString;
const cat = (item.length == 4) ? item[3] : "none";
db ~= Item(item[2], date, cat);
store(db);
}
 
void printLatest(in string[] a) {
auto db = load();
if (db.empty)
return writeln("No entries in database.");
db.sort!q{ a.date > b.date };
if (a.length == 3) {
foreach (item; db)
if (item.category == a[2])
writefln("%s, %s, %s", item.tupleof);
} else {
writefln("%s, %s, %s", db[0].tupleof);
}
}
 
void printAll() {
auto db = load();
if (db.empty)
return writeln("No entries in database.");
db.sort!q{ a.date < b.date };
foreach (item; db)
writefln("%s, %s, %s", item.tupleof);
}
 
Item[] load() {
Item[] db;
if (filename.exists && filename.isFile) {
try {
const text = filename.readText;
if (!text.empty)
db = csvReader!Item(text).array;
} catch (CSVException e) {
writeln(e.msg);
}
}
return db;
}
 
void store(in Item[] db) {
auto f = File(filename, "w+");
foreach (item; db)
f.writefln("%s,%s,%s", item.tupleof);
}
 
void printUsage() {
writeln(
`Usage:
simdb cmd [categoryName]
 
add add item, followed by optional category
latest print last added item(s), followed by optional category
all print all
 
For instance: add "some item name" "some category name"`);
}
}
 
void main(in string[] args) {
if (args.length < 2 || args.length > 4)
return printUsage();
 
switch (args[1].toLower) {
case "add": addItem(args); break;
case "latest": printLatest(args); break;
case "all": printAll(); break;
default: printUsage(); break;
}
}</syntaxhighlight>
{{out}}
<pre>C:\>simdb add item1 cat1
 
C:\>simdb add item2 cat2
 
C:\>simdb add item3 cat3
 
C:\>simdb add item4
 
C:\>simdb add item5
 
C:\>simdb add item6 cat4
 
C:\>simdb add item7 cat4
 
C:\>simdb latest
item7, 2014-06-04T16:02:01, cat4
 
C:\>simdb latest cat4
item7, 2014-06-04T16:02:01, cat4
item6, 2014-06-04T16:01:55, cat4
 
C:\>simdb all
item1, 2014-06-04T16:01:26, cat1
item2, 2014-06-04T16:01:34, cat2
item3, 2014-06-04T16:01:41, cat3
item4, 2014-06-04T16:01:46, none
item5, 2014-06-04T16:01:49, none
item6, 2014-06-04T16:01:55, cat4
item7, 2014-06-04T16:02:01, cat4
 
C:\>simdb add
Usage:
simdb cmd [categoryname]
 
add add item, followed by optional category
latest print last added item(s), followed by optional category
all print all
 
For instance: add "some item name" "some category name"</pre>
File:
<pre>item1,2014-06-04T16:01:26,cat1
item2,2014-06-04T16:01:34,cat2
item3,2014-06-04T16:01:41,cat3
item4,2014-06-04T16:01:46,none
item5,2014-06-04T16:01:49,none
item6,2014-06-04T16:01:55,cat4
item7,2014-06-04T16:02:01,cat4</pre>
 
=={{header|Emacs Lisp}}==
<syntaxhighlight lang="lisp">
(defun dbe-next-id ()
(unless (boundp '**dbe-current-id**) (setq **dbe-current-id** 1))
(let ((id **dbe-current-id**))
(cl-incf **dbe-current-id**)
id ) )
 
(defun dbe-rows (fn-handle-row &rest params)
(let ((has-more 't) current-line linum1 linum2
(fn-continue (plist-get params :continue)))
(save-window-excursion
(switch-to-buffer "**content**")
(beginning-of-buffer)
(if fn-continue (setq has-more (funcall fn-continue)))
(while has-more
(setq current-line
(buffer-substring (line-beginning-position)
(line-end-position)))
(unless (string= current-line "")
(funcall fn-handle-row (read current-line)))
(if fn-continue (setq has-more (funcall fn-continue)))
(setq linum1 (line-number-at-pos (point)))
(forward-line)
(setq linum2 (line-number-at-pos (point)))
(if (= linum1 linum2) (setq has-more nil))
)
)
)
)
(defun dbe-insert (row)
(interactive "xPlease enter the row data in plist format: ")
(save-window-excursion
(switch-to-buffer "**content**")
(end-of-buffer)
(let (row-data)
(setq row-data (append (list 'id (dbe-next-id)) (ensure-list row)))
(insert (format "%s\n" row-data))
(message ">> Row added: %s" row-data) ) ) )
 
(defun dbe-find-by-id (row-id)
(interactive "nPlease enter row id: ")
(let (row-found)
(dbe-rows (lambda (row)
(when (equal (plist-get row 'id) row-id)
(setq row-found row)) )
:continue (lambda () (null row-found)))
(message ">> Row found: %s" row-found)
)
)
</syntaxhighlight>
 
{{out}}
 
<pre>
M-x dbe-insert
Please enter the row data in plist format: (name "book1" author "author1")
>> Row added: (id 1 name book1 author author1)
 
M-x dbe-insert
Please enter the row data in plist format: (name "book2" author "author2")
>> Row added: (id 2 name book2 author author2)
 
M-x dbe-find-by-id
Please enter row id: 2
>> Row found: (id 2 name book2 author author2)
</pre>
 
=={{header|Erlang}}==
<syntaxhighlight lang="erlang">
#! /usr/bin/env escript
 
-compile({no_auto_import,[date/0]}).
 
main( ["add", Tag | Descriptions] ) -> add( date(), Tag, Descriptions );
main( ["add_date", Date, Tag | Descriptions] ) -> add( date_internal(string:tokens(Date, "-")), Tag, Descriptions );
main( ["print_latest"] ) -> print_latest( contents() );
main( ["print_latest_for_each"] ) -> print_latest_for_each( contents() );
main( ["print_all_date", Date] ) -> print_all_date( date_internal(string:tokens(Date, "-")), contents() );
main( _Error ) -> usage().
 
 
 
add( Date, Tag, Descriptions ) ->
Contents = contents(),
file:write_file( file(), io_lib:format("simple_database_v1.~n~p.~n", [[{Date, Tag, Descriptions} | Contents]]) ).
 
date() ->
{{Date, _Time}} = calendar:local_time(),
Date.
 
date_external( {Year, Month, Day} ) -> string:join( [erlang:integer_to_list(Year), erlang:integer_to_list(Month), erlang:integer_to_list(Day)], "-" );
date_external( _Error ) -> usage().
 
date_internal( [Year, Month, Day] ) -> {erlang:list_to_integer(Year), erlang:list_to_integer(Month), erlang:list_to_integer(Day)};
date_internal( _Error ) -> usage().
 
file() -> "simple_database_contents".
 
contents() -> contents( file:consult(file()) ).
 
contents( {ok, [simple_database_v1, Contents]} ) -> Contents;
contents( {error, Error} ) when is_atom(Error) -> [];
contents( {error, _Error} ) ->
io:fwrite( "Error: ~p corrupt. Starting from scratch~n", [file()] ),
[].
 
print_all_date( _Date, [] ) -> ok;
print_all_date( Date, Contents ) -> [print_latest([{D, Tag, Descriptions}]) || {D, Tag, Descriptions} <- Contents, D =:= Date].
 
print_latest( [] ) -> ok;
print_latest( [{Date, Tag, Descriptions} | _T] ) -> io:fwrite( "~s~n", [string:join( [date_external(Date), Tag | Descriptions], " ")] ).
 
print_latest_for_each( [] ) -> ok;
print_latest_for_each( Contents ) ->
Tags = lists:usort( [Tag || {_Date, Tag, _Descriptions} <- Contents] ),
[print_latest([lists:keyfind(X, 2, Contents)]) || X <- Tags].
 
usage() ->
io:fwrite( "Usage: ~p [add | add_date <date>] tag description ...~n", [escript:script_name()] ),
io:fwrite( "Or: ~p [print_latest | print_latest_for_each | print_all_date <date>]~n", [escript:script_name()] ),
io:fwrite( "Date format is YYYY-MM-DD~n" ),
io:fwrite( "Data stored in ~p~n", [file()] ),
init:stop().
</syntaxhighlight>
Command line session started with these file contents as database:
<pre>
simple_database_v1.
[{{2013,9,16},"comic",["hobbe"]},
{{2013,9,16},"comic",["gustaf"]}].
</pre>
Command line session:
<pre>
./simple_database add num 1 2 3
./simple_database add_date 1991-01-01 num 999 888
./simple_database print_latest
1991-1-1 num 999 888
./simple_database print_latest_for_each
2013-9-16 comic hobbe
1991-1-1 num 999 888
./simple_database print_all_date 2013-09-16
2013-9-16 num 1 2 3
2013-9-16 comic hobbe
2013-9-16 comic gustaf
</pre>
 
=={{header|Forth}}==
Simple in-memory database. Load/dump database from/to a file.
 
{{works with|GNU Forth|Gforth|0.7}}
Example file 'test.sdb':
<pre>
+: betty 1974.03.03;coworker;reading;
 
+: geea 1980.01.01;friend;sketch writer;
 
+: tom 1991.03.07;family member;reading;
 
+: alice 1987.09.01;coworker;classical music;
 
+: gammaQ3.14 3045.09.09;friend;watch movies, star walking;
</pre>
 
Example usage:
<pre>
$ gforth sdb.fs
 
help
 
[ -erased help message- ]
 
load test.sdb ok
 
.keys
 
gammaQ3.14 alice tom geea betty ok
 
betty .record betty 1974.03.03;coworker;reading; ok
 
newline geea .record
 
geea 1980.01.01;friend;sketch writer; ok
 
+: theea 1979.04.05;coworker;astronomy; ok
 
newline .bydate
 
gammaQ3.14 3045.09.09;friend;watch movies, star walking;
 
tom 1991.03.07;family member;reading;
 
alice 1987.09.01;coworker;classical music;
 
geea 1980.01.01;friend;sketch writer;
 
theea 1979.04.05;coworker;astronomy;
 
betty 1974.03.03;coworker;reading;
 
dump t2.sdb ok
 
bye
 
$
 
$ cat t2.sdb
 
+: betty 1974.03.03;coworker;reading;
 
+: geea 1980.01.01;friend;sketch writer;
 
+: tom 1991.03.07;family member;reading;
 
+: alice 1987.09.01;coworker;classical music;
 
+: gammaQ3.14 3045.09.09;friend;watch movies, star walking;
 
+: theea 1979.04.05;coworker;astronomy;
 
$
</pre>
 
Code:
<syntaxhighlight lang="forth">\ sdb.fs Simple database. Gforth 0.7.0 specific
' noop is bootmessage
 
wordlist constant USER: \ USER functions
wordlist constant SDB \ DB keys
wordlist constant FIELDS \ DB fields
 
: -SDB?EXIT ( -- ; Continue if `SDB' non-empty )
SDB cell+ @ 0= IF rdrop exit THEN ;
 
\ MACROS
: |comp| ( MACRO: | code to be compiled | )
char parse evaluate ; immediate
: LIST ( node -- ) ]] BEGIN @ dup WHILE >R [[ ; immediate
: LOOP-LIST ( -- ) ]] R> REPEAT drop [[ ; immediate
: UNLIST ( -- ) POSTPONE rdrop ; immediate
 
\ Helper words
: .; [char] ; emit ;
: !+ dup cell+ -rot ! ;
: ($+) ( cas us cad ud -- cad us+ud ; append source string to destination )
swap >R 2dup + R> swap >R tuck + swap >R swap move R> R> ;
 
\ --- Working Record Fields
current @ FIELDS current !
2variable person
2variable birthday
2variable relationship
2variable hobby
current ! FIELDS >order
 
\ --- Ring list
: new-node ( -- node ; root of circular list )
here dup , ;
: do-link ( node new-node -- ; do link after current node )
over @ over ! swap ! ;
: empty-ring? ( node -- f ) dup @ = ;
 
: RING ( node -- ) ]] dup BEGIN @ 2dup <> WHILE 2>R [[ ; immediate
: LOOP-RING ( -- ) ]] 2R> REPEAT 2drop [[ ; immediate
: UNRING ( -- ) postpone 2RDROP ; immediate
 
:noname
s" " person 2! s" 9999.01.01" birthday 2! s" " relationship 2! s" " hobby 2! ;
new-node swap , CONSTANT OLD
 
\ --- Insertion into ring
: node>xt ( node -- xt ) cell+ @ ;
: bday@ ( node -- ca u ) node>xt execute birthday 2@ ;
: datecmp ( node node -- -1|0|1 ) bday@ rot bday@ compare ;
 
: search-by-date ( new-node node -- node' ; Linear search by birth date )
dup
RING ( new-node node )
over I datecmp 0<
IF nip UNRING exit
ELSE drop I THEN
LOOP-RING nip ;
 
: insert-ordered ( new-node -- )
OLD dup empty-ring? 0=
IF over swap search-by-date THEN swap do-link ;
 
\ --- Field compiling
: fld: [char] ; parse postpone sliteral ; immediate
 
: _sdb-walk ( MACRO: | xt[--] -- | )
]] -SDB?EXIT here dup SDB cell+
LIST I name>int swap !+ LOOP-LIST [[ 1 cells ]] literal -
DO I @ |comp| [[ -1 cells ]] literal +LOOP [[ ; immediate
 
2variable category
: msg_nocategory ( -- )
." No such category!" cr ;
 
\ --- USER definitions
user: >order current @ USER: current !
: bye bye ;
: .s .s ;
: newline cr ;
: godb SDB >order ;
: .keys SDB wordlist-words ;
: .person person 2@ type ;
: .birthday birthday 2@ type ;
: .relationship relationship 2@ type ;
: .hobby hobby 2@ type ;
: .record .person 1 spaces .birthday .; .relationship .; .hobby .; ;
 
: .last SDB cell+ @ dup
IF name>int execute .record ELSE drop THEN ;
 
: .lastbycategory ( "field-name" -- )
here 0 category 2! parse-name FIELDS search-wordlist
IF sdb cell+
LIST ( xt )
I name>int execute dup execute 2@ category 2@ 2swap search nip nip 0=
IF .record cr dup execute 2@ category 2@ ($+) category 2! THEN
LOOP-LIST drop
ELSE ['] msg_nocategory stderr OUTFILE-EXECUTE THEN ;
 
: .bydate ( -- )
OLD RING I node>xt execute .record cr LOOP-RING ;
 
: .sdb _sdb-walk | execute .record cr | ;
: sdb-dump _sdb-walk | execute ." +: " .record cr | ;
 
: dump ( "db-file" -- )
parse-name w/o
CREATE-FILE throw dup
['] sdb-dump swap OUTFILE-EXECUTE
CLOSE-FILE throw ;
 
: load ( "db-file" -- ) include ;
 
: +: ( "person birth-day;relationship;hobby; -- )
new-node dup cell+ >R 0 , \ post `xt'
current @ SDB current ! \ compile into `sdb' wordlist
: latestxt dup R> ! \ fix-up `xt'
]] literal >name name>string person 2! fld: birthday 2! fld: relationship 2! fld: hobby 2! ; [[
current !
insert-ordered ;
 
: HELP cr
cr ." KEYWORDS: " USER: wordlist-words cr ." ---"
cr ." Prefix `.' means print"
cr ." To add a record, type: +: name yyyy.mm.dd;relationship;hobby;"
cr cr ;
current !
SEAL godb</syntaxhighlight>
 
=={{header|Go}}==
<syntaxhighlight lang="go">package main
 
import (
"encoding/json"
"fmt"
"io"
"os"
"sort"
"strings"
"time"
"unicode"
)
 
// Database record format. Time stamp and name are required.
// Tags and notes are optional.
type Item struct {
Stamp time.Time
Name string
Tags []string `json:",omitempty"`
Notes string `json:",omitempty"`
}
 
// Item implements stringer interface
func (i *Item) String() string {
s := i.Stamp.Format(time.ANSIC) + "\n Name: " + i.Name
if len(i.Tags) > 0 {
s = fmt.Sprintf("%s\n Tags: %v", s, i.Tags)
}
if i.Notes > "" {
s += "\n Notes: " + i.Notes
}
return s
}
 
// collection of Items
type db []*Item
 
// db implements sort.Interface
func (d db) Len() int { return len(d) }
func (d db) Swap(i, j int) { d[i], d[j] = d[j], d[i] }
func (d db) Less(i, j int) bool { return d[i].Stamp.Before(d[j].Stamp) }
 
// hard coded database file name
const fn = "sdb.json"
 
func main() {
if len(os.Args) == 1 {
latest()
return
}
switch os.Args[1] {
case "add":
add()
case "latest":
latest()
case "tags":
tags()
case "all":
all()
case "help":
help()
default:
usage("unrecognized command")
}
}
 
func usage(err string) {
if err > "" {
fmt.Println(err)
}
fmt.Println(`usage: sdb [command] [data]
where command is one of add, latest, tags, all, or help.`)
}
 
func help() {
usage("")
fmt.Println(`
Commands must be in lower case.
If no command is specified, the default command is latest.
 
Latest prints the latest item.
All prints all items in chronological order.
Tags prints the lastest item for each tag.
Help prints this message.
 
Add adds data as a new record. The format is,
 
name [tags] [notes]
 
Name is the name of the item and is required for the add command.
 
Tags are optional. A tag is a single word.
A single tag can be specified without enclosing brackets.
Multiple tags can be specified by enclosing them in square brackets.
 
Text remaining after tags is taken as notes. Notes do not have to be
enclosed in quotes or brackets. The brackets above are only showing
that notes are optional.
 
Quotes may be useful however--as recognized by your operating system shell
or command line--to allow entry of arbitrary text. In particular, quotes
or escape characters may be needed to prevent the shell from trying to
interpret brackets or other special characters.
 
Examples:
sdb add Bookends // no tags, no notes
sdb add Bookends rock my favorite // tag: rock, notes: my favorite
sdb add Bookends [rock folk] // two tags
sdb add Bookends [] "Simon & Garfunkel" // notes, no tags
sdb add "Simon&Garfunkel [artist]" // name: Simon&Garfunkel, tag: artist
As shown in the last example, if you use features of your shell to pass
all data as a single string, the item name and tags will still be identified
by separating whitespace.
The database is stored in JSON format in the file "sdb.json"
`)
}
 
// load data for read only purposes.
func load() (db, bool) {
d, f, ok := open()
if ok {
f.Close()
if len(d) == 0 {
fmt.Println("no items")
ok = false
}
}
return d, ok
}
 
// open database, leave open
func open() (d db, f *os.File, ok bool) {
var err error
f, err = os.OpenFile(fn, os.O_RDWR|os.O_CREATE, 0666)
if err != nil {
fmt.Println("cant open??")
fmt.Println(err)
return
}
jd := json.NewDecoder(f)
err = jd.Decode(&d)
// EOF just means file was empty. That's okay with us.
if err != nil && err != io.EOF {
fmt.Println(err)
f.Close()
return
}
ok = true
return
}
 
// handle latest command
func latest() {
d, ok := load()
if !ok {
return
}
sort.Sort(d)
fmt.Println(d[len(d)-1])
}
 
// handle all command
func all() {
d, ok := load()
if !ok {
return
}
sort.Sort(d)
for _, i := range d {
fmt.Println("-----------------------------------")
fmt.Println(i)
}
fmt.Println("-----------------------------------")
}
 
// handle tags command
func tags() {
d, ok := load()
if !ok {
return
}
// we have to traverse the entire list to collect tags so there
// is no point in sorting at this point.
// collect set of unique tags associated with latest item for each
latest := make(map[string]*Item)
for _, item := range d {
for _, tag := range item.Tags {
li, ok := latest[tag]
if !ok || item.Stamp.After(li.Stamp) {
latest[tag] = item
}
}
}
// invert to set of unique items, associated with subset of tags
// for which the item is the latest.
type itemTags struct {
item *Item
tags []string
}
inv := make(map[*Item][]string)
for tag, item := range latest {
inv[item] = append(inv[item], tag)
}
// now we sort just the items we will output
li := make(db, len(inv))
i := 0
for item := range inv {
li[i] = item
i++
}
sort.Sort(li)
// finally ready to print
for _, item := range li {
tags := inv[item]
fmt.Println("-----------------------------------")
fmt.Println("Latest item with tags", tags)
fmt.Println(item)
}
fmt.Println("-----------------------------------")
}
// handle add command
func add() {
if len(os.Args) < 3 {
usage("add command requires data")
return
} else if len(os.Args) == 3 {
add1()
} else {
add4()
}
}
 
// add command with one data string. look for ws as separators.
func add1() {
data := strings.TrimLeftFunc(os.Args[2], unicode.IsSpace)
if data == "" {
// data must have at least some non-whitespace
usage("invalid name")
return
}
sep := strings.IndexFunc(data, unicode.IsSpace)
if sep < 0 {
// data consists only of a name
addItem(data, nil, "")
return
}
name := data[:sep]
data = strings.TrimLeftFunc(data[sep:], unicode.IsSpace)
if data == "" {
// nevermind trailing ws, it's still only a name
addItem(name, nil, "")
return
}
if data[0] == '[' {
sep = strings.Index(data, "]")
if sep < 0 {
// close bracketed list for the user. no notes.
addItem(name, strings.Fields(data[1:]), "")
} else {
// brackets make things easy
addItem(name, strings.Fields(data[1:sep]),
strings.TrimLeftFunc(data[sep+1:], unicode.IsSpace))
}
return
}
sep = strings.IndexFunc(data, unicode.IsSpace)
if sep < 0 {
// remaining word is a tag
addItem(name, []string{data}, "")
} else {
// there's a tag and some data
addItem(name, []string{data[:sep]},
strings.TrimLeftFunc(data[sep+1:], unicode.IsSpace))
}
}
 
// add command with multiple strings remaining on command line
func add4() {
name := os.Args[2]
tag1 := os.Args[3]
if tag1[0] != '[' {
// no brackets makes things easy
addItem(name, []string{tag1}, strings.Join(os.Args[4:], " "))
return
}
if tag1[len(tag1)-1] == ']' {
// tags all in one os.Arg is easy too
addItem(name, strings.Fields(tag1[1:len(tag1)-1]),
strings.Join(os.Args[4:], " "))
return
}
// start a list for tags
var tags []string
if tag1 > "[" {
tags = []string{tag1[1:]}
}
for x, tag := range os.Args[4:] {
if tag[len(tag)-1] != ']' {
tags = append(tags, tag)
} else {
// found end of tag list
if tag > "]" {
tags = append(tags, tag[:len(tag)-1])
}
addItem(name, tags, strings.Join(os.Args[5+x:], " "))
return
}
}
// close bracketed list for the user. no notes.
addItem(name, tags, "")
}
 
// complete the add command
func addItem(name string, tags []string, notes string) {
db, f, ok := open()
if !ok {
return
}
defer f.Close()
// add the item and format JSON
db = append(db, &Item{time.Now(), name, tags, notes})
sort.Sort(db)
js, err := json.MarshalIndent(db, "", " ")
if err != nil {
fmt.Println(err)
return
}
// time to overwrite the file
if _, err = f.Seek(0, 0); err != nil {
fmt.Println(err)
return
}
f.Truncate(0)
if _, err = f.Write(js); err != nil {
fmt.Println(err)
}
}</syntaxhighlight>
 
=={{header|Haskell}}==
 
The database is a list of type Item stored in a StateT monad transformer that allows for IO actions to be perfomed with it (StateT [Item] IO a). All IO actions occurring inside the StateT monad (handling command line arguments and printing items) must be lifted.
The database is written to disk using "show" and read back using "read". Therefore, Item is declared as an instance of both Show and Read classes. An item in the database file looks like the following:
Item {description = "La traviata", category = ["Classical"], date = Date 2012 10 19, optional = ["Giuseppe Verdi","1853"]}
 
<syntaxhighlight lang="haskell">import Control.Monad.State
import Data.List (sortBy, nub)
import System.Environment (getArgs, getProgName)
import System.Directory (doesFileExist)
import System.IO (openFile, hGetContents, hClose, IOMode(..),
Handle, hPutStrLn)
 
-- for storing dates
data Date = Date Integer Int Int deriving (Show, Read, Eq, Ord)
 
-- for storing database items
data Item = Item {description :: String
,category :: [String]
,date :: Date
,optional :: [String]}
deriving (Show, Read)
 
-- a state monad transformer which wraps IO actions.
-- the database (state) is passed implicitly between functions.
type ItemList a = StateT [Item] IO a
 
-- add an item to the database
addItem :: Item -> ItemList ()
addItem i = modify (++ [i])
 
-- get the newest of a list of items
latest :: [Item] -> [Item]
latest [] = []
latest [x]= [x]
latest xs = take 1 $ sortBy newer xs
 
-- compare two items to see which one is newer
newer :: Item -> Item -> Ordering
newer a b = compare (date b) (date a)
 
-- list all different categories (no duplicates)
categories :: ItemList [String]
categories = liftM (nub . concatMap category) get
 
-- list only the items with the given category tag
filterByCategory :: String -> ItemList [Item]
filterByCategory c = liftM (filter (\i -> c `elem` category i)) get
 
-- get the newest of all items
lastOfAll :: ItemList [Item]
lastOfAll = liftM latest get
-- get the newest item in each category
latestByCategory :: ItemList [Item]
latestByCategory = do
cats <- categories
filt <- mapM filterByCategory cats
return $ concatMap latest filt
 
-- sort all items chronologically, newest first
sortByDate :: ItemList [Item]
sortByDate = liftM (sortBy newer) get
 
toScreen :: Item -> IO ()
toScreen (Item desc cats (Date y m d) opt) = putStrLn $
"Description:\t" ++ desc ++ "\nCategories:\t" ++ show cats ++
"\nDate:\t\t" ++ show y ++ "-" ++ show m ++ "-" ++ show d ++
"\nOther info:\t" ++ show opt
 
-- command line argument handling
-- if the user called the program with the option "add", the
-- new item is returned to main so that it can be saved to disk.
-- the argument "opt" is a list.
arguments :: ItemList [Item]
arguments = do
args <- liftIO getArgs
case args of
("add":desc:cat:year:month:day:opt) -> do
let newItem = parseItem args
addItem newItem
return [newItem]
("latest":[]) -> do
item <- lastOfAll
lift $ mapM_ toScreen item
return []
("category":[]) -> do
items <- latestByCategory
lift $ mapM_ toScreen items
return []
("all":[]) -> do
sorted <- sortByDate
lift $ mapM_ toScreen sorted
return []
_ -> do
lift usage
return []
 
parseItem :: [String] -> Item
parseItem (_:desc:cat:year:month:day:opt) =
Item {description = desc, category = words cat,
date = Date (read year) (read month) (read day),
optional = opt}
usage :: IO ()
usage = do
progName <- getProgName
putStrLn $ "Usage: " ++ progName ++ " add|all|category|latest \
\OPTIONS\n\nadd \"description\" \"category1 category2\"... \
\year month day [\"note1\" \"note2\"...]\n\tAdds a new record \
\to the database.\n\nall\n\tPrints all items in chronological \
\order.\n\ncategory\n\tPrints the latest item for each category.\
\\n\nlatest\n\tPrints the latest item."
 
-- the program creates, reads and writes to a file in the current directory
main :: IO ()
main = do
progName <- getProgName
let fileName = progName ++ ".db"
e <- doesFileExist fileName
if e
then do
hr <- openFile fileName ReadMode
f <- hGetContents hr
v <- evalStateT arguments (map read $ lines f)
hClose hr -- must be called after working with contents!
hw <- openFile fileName AppendMode
mapM_ (hPutStrLn hw . show) v
hClose hw
else do
v <- evalStateT arguments []
hw <- openFile fileName WriteMode
mapM_ (hPutStrLn hw . show) v
hClose hw
</syntaxhighlight>
 
=={{header|J}}==
 
J comes with a sql database, jdb. Jdb's columns are memory mapped files with header information. These won't meet the human readable data file requirement. Hence, this program:
 
<syntaxhighlight lang="j">HELP=: 0 :0
Commands:
 
DBNAME add DATA
DBNAME display the latest entry
DBNAME display the latest entry where CATEGORY contains WORD
DBNAME display all entries
DBNAME display all entries order by CATEGORY
 
1) The first add with new DBNAME assign category names.
2) lower case arguments verbatim.
3) UPPER CASE: substitute your values.
 
Examples, having saved this program as a file named s :
$ jconsole s simple.db display all entries
$ jconsole s simple.db add "first field" "2nd field"
)
 
Q=: '''' NB. quote character
time=: 6!:0@:('YYYY-MM-DD:hh:mm:ss.sss'"_)
 
embed=: >@:{.@:[ , ] , >@:{:@:[
assert '(x+y)' -: '()' embed 'x+y'
 
Duplicate=: 1 :'#~ m&= + 1 #~ #'
assert 0 1 2 3 3 4 -: 3 Duplicate i.5
 
prepare=: LF ,~ [: }:@:; (Q;Q,';')&embed@:(Q Duplicate)&.>@:(;~ time)
assert (-: }.@:".@:}:@:prepare) 'boxed';'';'li''st';'of';'''strings'''
 
categorize=: dyad define
i=. x i. y
if. (1 (~: #) i) +. i (= #) x do.
smoutput 'choose 1 of'
smoutput x
exit 1
end.
{. i NB. "index of" frame has rank 1.
)
assert 0 -: 'abc' categorize 'a'
 
loadsdb=: (<'time') (<0 0)} ".;._2@:(1!:1)
 
Dispatch=: conjunction define
help
:
commands=. y
command=. {. commands
x (u`help@.(command(i.~ ;:)n)) }.commands
)
 
NB. the long fork in show groups (": #~ (1 1 embed (1j1 }:@:# (1 #~ #))))
show=: smoutput@:(": #~ 1 1 embed 1j1 }:@:# 1 #~ #)
 
in=: +./@:E.
assert 'the' in'quick brown fox jumps over the lazy dog'
assert 'the'-.@:in'QUICK BROWN FOX JUMPS OVER THE LAZY DOG'
 
where=: dyad define
'category contains word'=. 3 {. y
if. 'contains' -.@:-: contains do.
help''
exit 1
end.
i=. x ({.@:[ categorize <@:]) category
j=. {: I. ; word&in&.> i {"1 x
if. 0 (= #) j do.
smoutput 'no matches'
else.
x (show@:{~ 0&,) j
end.
)
 
entry=: 4 : 0
if. a: = y do.
show@:({. ,: {:) x
else.
x ''`where Dispatch'where' y
end.
)
 
latest=: ''`entry Dispatch'entry'
the=: ''`latest Dispatch'latest'
 
by=: 4 : 0
i=. x (categorize~ {.)~ y
show ({. , (/: i&{"1)@:}.) x
)
 
order=: ''`by Dispatch'by'
 
entries=: 4 : 0
if. a: = y do.
show x
else.
x ''`order Dispatch'order' y
end.
)
 
all=: ''`entries Dispatch'entries'
 
help=: smoutput@:(HELP"_)
add=: 1!:3~ prepare NB. minimal---no error tests
display=: (the`all Dispatch'the all'~ loadsdb)~ NB. load the simple db for some sort of display
 
({. add`display Dispatch'add display' }.)@:(2&}.)ARGV
 
exit 0
</syntaxhighlight>
Assume the j code is stored in file s . These bash commands, stored in file input , create a database using add .
<syntaxhighlight lang="sh">D='jconsole s dataflow'
$D add name expression algebraic rank valence example explanation
$D add insert 'f/ y' 'insert f within y' infinite dyad 'sum=: +/' 'continued_fraction=:+`%/'
$D add fork '(f g h)y' 'g(f(y),h(y))' infinite monad 'average=: +/ % #' 'sum divided by tally'
$D add hook '(f g)y' 'f(y,g(y))' infinite monad '(/: 2&{"1)table' 'sort by third column'
$D add hook 'x(f g)y' 'f(x,g(y))' infinite dyad 'display verb in s' 'a reflexive dyadic hook'
$D add fork 'x(f g h)y' 'g(f(x,y),h(x,y))' infinite dyad '2j1(+ * -)9 12' 'product of sum and difference'
$D add reflexive 'f~ y' 'f(y,y)' infinite monad '^~y' 'y raised to the power of y'
$D add passive 'x f~ y' 'f(y,x)' 'ranks of f' dyad '(%~ i.@:>:) 8x' '8 intervals from 0 to 1'
$D add atop 'f@g y' 'f(g(y))' 'rank of g' monad '*:@(+/)' 'square the sum'
$D add atop 'x f@g y' 'f(g(x,y))' 'rank of g' dyad '>@{.' '(lisp) open the car'
$D add 'many more!'
</syntaxhighlight>
Now we look up data from the bash command line.
<syntaxhighlight lang="sh">
$ . input # source the input
$ echo $D
jconsole s dataflow
$ $D display the latest entry
┌───────────────────────┬──────────┬──────────┬─────────┬────┬───────┬───────┬───────────┐
│time │name │expression│algebraic│rank│valence│example│explanation│
│2012-02-07:20:36:54.749│many more!│ │ │ │ │ │ │
└───────────────────────┴──────────┴──────────┴─────────┴────┴───────┴───────┴───────────┘
$ $D display the latest entry where 'part of speech' contains verb
choose 1 of
┌────┬────┬──────────┬─────────┬────┬───────┬───────┬───────────┐
│time│name│expression│algebraic│rank│valence│example│explanation│
└────┴────┴──────────┴─────────┴────┴───────┴───────┴───────────┘
$ $D display the latest entry where example contains average
┌───────────────────────┬────┬──────────┬────────────┬────────┬───────┬────────────────┬────────────────────┐
│time │name│expression│algebraic │rank │valence│example │explanation │
│2012-02-07:20:36:54.564│fork│(f g h)y │g(f(y),h(y))│infinite│monad │average=: +/ % #│sum divided by tally│
└───────────────────────┴────┴──────────┴────────────┴────────┴───────┴────────────────┴────────────────────┘
$ $D display all entries ordre by valence # oops! transposition typo.
Commands:
 
DBNAME add DATA
DBNAME display the latest entry
DBNAME display the latest entry where CATEGORY contains WORD
DBNAME display all entries
DBNAME display all entries order by CATEGORY
 
1) The first add with new DBNAME assign category names.
2) lower case arguments verbatim.
3) UPPER CASE: substitute your values.
 
Examples, having saved this program as a file named s :
$ jconsole s simple.db display all entries
$ jconsole s simple.db add "first field" "2nd field"
 
$ $D display all entries order by valence
┌───────────────────────┬──────────┬──────────┬─────────────────┬──────────┬───────┬─────────────────┬─────────────────────────────┐
│time │name │expression│algebraic │rank │valence│example │explanation │
│2012-02-08:23:45:06.539│many more!│ │ │ │ │ │ │
│2012-02-08:23:45:06.329│insert │f/ y │insert f within y│infinite │dyad │sum=: +/ │continued_fraction=:+`%/ │
│2012-02-08:23:45:06.400│hook │x(f g)y │f(x,g(y)) │infinite │dyad │display verb in s│a reflexive dyadic hook │
│2012-02-08:23:45:06.426│fork │x(f g h)y │g(f(x,y),h(x,y)) │infinite │dyad │2j1(+ * -)9 12 │product of sum and difference│
│2012-02-08:23:45:06.471│passive │x f~ y │f(y,x) │ranks of f│dyad │(%~ i.@:>:) 8x │8 intervals from 0 to 1 │
│2012-02-08:23:45:06.515│atop │x f@g y │f(g(x,y)) │rank of g │dyad │>@{. │(lisp) open the car │
│2012-02-08:23:45:06.353│fork │(f g h)y │g(f(y),h(y)) │infinite │monad │average=: +/ % # │sum divided by tally │
│2012-02-08:23:45:06.376│hook │(f g)y │f(y,g(y)) │infinite │monad │(/: 2&{"1)table │sort by third column │
│2012-02-08:23:45:06.448│reflexive │f~ y │f(y,y) │infinite │monad │^~y │y raised to the power of y │
│2012-02-08:23:45:06.493│atop │f@g y │f(g(y)) │rank of g │monad │*:@(+/) │square the sum │
└───────────────────────┴──────────┴──────────┴─────────────────┴──────────┴───────┴─────────────────┴─────────────────────────────┘
$ $D display all entries
┌───────────────────────┬──────────┬──────────┬─────────────────┬──────────┬───────┬─────────────────┬─────────────────────────────┐
│time │name │expression│algebraic │rank │valence│example │explanation │
│2012-02-08:23:45:06.329│insert │f/ y │insert f within y│infinite │dyad │sum=: +/ │continued_fraction=:+`%/ │
│2012-02-08:23:45:06.353│fork │(f g h)y │g(f(y),h(y)) │infinite │monad │average=: +/ % # │sum divided by tally │
│2012-02-08:23:45:06.376│hook │(f g)y │f(y,g(y)) │infinite │monad │(/: 2&{"1)table │sort by third column │
│2012-02-08:23:45:06.400│hook │x(f g)y │f(x,g(y)) │infinite │dyad │display verb in s│a reflexive dyadic hook │
│2012-02-08:23:45:06.426│fork │x(f g h)y │g(f(x,y),h(x,y)) │infinite │dyad │2j1(+ * -)9 12 │product of sum and difference│
│2012-02-08:23:45:06.448│reflexive │f~ y │f(y,y) │infinite │monad │^~y │y raised to the power of y │
│2012-02-08:23:45:06.471│passive │x f~ y │f(y,x) │ranks of f│dyad │(%~ i.@:>:) 8x │8 intervals from 0 to 1 │
│2012-02-08:23:45:06.493│atop │f@g y │f(g(y)) │rank of g │monad │*:@(+/) │square the sum │
│2012-02-08:23:45:06.515│atop │x f@g y │f(g(x,y)) │rank of g │dyad │>@{. │(lisp) open the car │
│2012-02-08:23:45:06.539│many more!│ │ │ │ │ │ │
└───────────────────────┴──────────┴──────────┴─────────────────┴──────────┴───────┴─────────────────┴─────────────────────────────┘
$ cat dataflow
'2012-02-08:23:45:06.304';'name';'expression';'algebraic';'rank';'valence';'example';'explanation'
'2012-02-08:23:45:06.329';'insert';'f/ y';'insert f within y';'infinite';'dyad';'sum=: +/';'continued_fraction=:+`%/'
'2012-02-08:23:45:06.353';'fork';'(f g h)y';'g(f(y),h(y))';'infinite';'monad';'average=: +/ % #';'sum divided by tally'
'2012-02-08:23:45:06.376';'hook';'(f g)y';'f(y,g(y))';'infinite';'monad';'(/: 2&{"1)table';'sort by third column'
'2012-02-08:23:45:06.400';'hook';'x(f g)y';'f(x,g(y))';'infinite';'dyad';'display verb in s';'a reflexive dyadic hook'
'2012-02-08:23:45:06.426';'fork';'x(f g h)y';'g(f(x,y),h(x,y))';'infinite';'dyad';'2j1(+ * -)9 12';'product of sum and difference'
'2012-02-08:23:45:06.448';'reflexive';'f~ y';'f(y,y)';'infinite';'monad';'^~y';'y raised to the power of y'
'2012-02-08:23:45:06.471';'passive';'x f~ y';'f(y,x)';'ranks of f';'dyad';'(%~ i.@:>:) 8x';'8 intervals from 0 to 1'
'2012-02-08:23:45:06.493';'atop';'f@g y';'f(g(y))';'rank of g';'monad';'*:@(+/)';'square the sum'
'2012-02-08:23:45:06.515';'atop';'x f@g y';'f(g(x,y))';'rank of g';'dyad';'>@{.';'(lisp) open the car'
'2012-02-08:23:45:06.539';'many more!'
$ </syntaxhighlight>
 
=={{header|Java}}==
{{trans|D}}
{{works with|Java|7}}
<syntaxhighlight lang="java">import java.io.*;
import java.text.*;
import java.util.*;
 
public class SimpleDatabase {
 
final static String filename = "simdb.csv";
 
public static void main(String[] args) {
if (args.length < 1 || args.length > 3) {
printUsage();
return;
}
 
switch (args[0].toLowerCase()) {
case "add":
addItem(args);
break;
case "latest":
printLatest(args);
break;
case "all":
printAll();
break;
default:
printUsage();
break;
}
}
 
private static class Item implements Comparable<Item>{
final String name;
final String date;
final String category;
 
Item(String n, String d, String c) {
name = n;
date = d;
category = c;
}
 
@Override
public int compareTo(Item item){
return date.compareTo(item.date);
}
 
@Override
public String toString() {
return String.format("%s,%s,%s%n", name, date, category);
}
}
 
private static void addItem(String[] input) {
if (input.length < 2) {
printUsage();
return;
}
List<Item> db = load();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String date = sdf.format(new Date());
String cat = (input.length == 3) ? input[2] : "none";
db.add(new Item(input[1], date, cat));
store(db);
}
 
private static void printLatest(String[] a) {
List<Item> db = load();
if (db.isEmpty()) {
System.out.println("No entries in database.");
return;
}
Collections.sort(db);
if (a.length == 2) {
for (Item item : db)
if (item.category.equals(a[1]))
System.out.println(item);
} else {
System.out.println(db.get(0));
}
}
 
private static void printAll() {
List<Item> db = load();
if (db.isEmpty()) {
System.out.println("No entries in database.");
return;
}
Collections.sort(db);
for (Item item : db)
System.out.println(item);
}
 
private static List<Item> load() {
List<Item> db = new ArrayList<>();
try (Scanner sc = new Scanner(new File(filename))) {
while (sc.hasNext()) {
String[] item = sc.nextLine().split(",");
db.add(new Item(item[0], item[1], item[2]));
}
} catch (IOException e) {
System.out.println(e);
}
return db;
}
 
private static void store(List<Item> db) {
try (FileWriter fw = new FileWriter(filename)) {
for (Item item : db)
fw.write(item.toString());
} catch (IOException e) {
System.out.println(e);
}
}
 
private static void printUsage() {
System.out.println("Usage:");
System.out.println(" simdb cmd [categoryName]");
System.out.println(" add add item, followed by optional category");
System.out.println(" latest print last added item(s), followed by "
+ "optional category");
System.out.println(" all print all");
System.out.println(" For instance: add \"some item name\" "
+ "\"some category name\"");
}
}</syntaxhighlight>
 
Output:
 
<pre>
C:\temp>java -jar SimpleDatabase.jar add item1
 
C:\temp>java -jar SimpleDatabase.jar add item2
 
C:\temp>java -jar SimpleDatabase.jar add item3 cat3
 
C:\temp>java -jar SimpleDatabase.jar add item4 cat3
 
C:\temp>java -jar SimpleDatabase.jar add item5 cat3
 
C:\temp>java -jar SimpleDatabase.jar latest
item1,2014-06-03 19:30:05,none
 
C:\temp>java -jar SimpleDatabase.jar latest cat3
item3,2014-06-03 19:30:14,cat3
 
item4,2014-06-03 19:30:20,cat3
 
item5,2014-06-03 19:30:23,cat3
 
C:\temp>java -jar SimpleDatabase.jar all
item1,2014-06-03 19:30:05,none
 
item2,2014-06-03 19:30:08,none
 
item3,2014-06-03 19:30:14,cat3
 
item4,2014-06-03 19:30:20,cat3
 
item5,2014-06-03 19:30:23,cat3</pre>
 
=={{header|Julia}}==
Command line CSV based simple database. The file used contained:<pre>
Name,Birthdate,State,Relation,Email
Sally Whittaker,1988-12-05,Illinois,friend,sally@mail.com
Belinda Jameson,1994-02-17,California,family,beljames@example.com
Jeff Bragg,2018-10-10,Texas,family,jb@texas.edu
Sandy Allen,2002-03-09,Colorado,friend,sandya@mail.com
Fred Kobo,1967-10-10,Colorado,friend,fkobo@example.net</pre>
<syntaxhighlight lang="julia">using CSV, DataFrames, ArgParse, Dates
 
setting = ArgParseSettings()
@add_arg_table setting begin
"--add"
help = "add an entry, within double quotes, comma separated as \"name,birthdate,state,relation,email\" with birthdate as yyyy-mm-dd"
"--latest"
action = :store_true
nargs = 0
help = "print latest (last) entry"
"--latestfriend"
action = :store_true
nargs = 0
help = "print last friend listed"
"--latestfamily"
action = :store_true
nargs = 0
help = "print last family member listed"
"--listbyage"
action = :store_true
nargs = 0
help = "print all ages and entries in birth order"
end
 
const filename = "example.csv"
const df = CSV.File(filename, dateformat="yyyy-mm-dd") |> DataFrame
const commands = parse_args(setting)
if length(ARGS) == 0
ArgParse.show_help(setting)
end
const changeflag = [false]
 
for (k, v) in commands
if k == "add" && v != nothing
newrow = Vector{Any}(split(v, r","))
if length(newrow) == 5 && tryparse(DateTime, newrow[2]) != nothing
newrow[2] = DateTime(newrow[2])
push!(df, newrow)
changeflag[1] = true
println("Added entry $newrow.")
end
elseif k == "latest" && v
println("The latest entry is $(df[end, :])")
elseif k == "latestfriend" && v
println(df[df.Relation .== "friend", :][end, :])
elseif k == "latestfamily" && v
println(df[df.Relation .== "family", :][end, :])
elseif k == "listbyage" && v
dobcol = df[:Birthdate]
age = map(x -> round((now() - DateTime(x)).value /(1000*3600*24*365.25), digits=1), dobcol)
df2 = deepcopy(df)
df2 = insert!(df, 1, age, :Age)
println(sort(df2, (:Age)))
end
end
 
if changeflag[1]
CSV.write(filename, df)
println("Changes written to file $filename.")
end
</syntaxhighlight>
 
=={{header|Kotlin}}==
{{trans|Java}}
... though not quite the same.
<syntaxhighlight lang="scala">// version 1.2.31
 
import java.text.SimpleDateFormat
import java.util.Date
import java.io.File
import java.io.IOException
 
val file = File("simdb.csv")
 
class Item(
val name: String,
val date: String,
val category: String
) : Comparable<Item> {
 
override fun compareTo(other: Item) = date.compareTo(other.date)
 
override fun toString() = "$name, $date, $category"
}
 
fun addItem(input: Array<String>) {
if (input.size < 2) {
printUsage()
return
}
val sdf = SimpleDateFormat("yyyy-MM-dd HH:mm:ss")
val date = sdf.format(Date())
val cat = if (input.size == 3) input[2] else "none"
store(Item(input[1], date, cat))
}
 
fun printLatest(a: Array<String>) {
val db = load()
if (db.isEmpty()) {
println("No entries in database.")
return
}
// no need to sort db as items are added chronologically
if (a.size == 2) {
var found = false
for (item in db.reversed()) {
if (item.category == a[1]) {
println(item)
found = true
break
}
}
if (!found) println("There are no items for category '${a[1]}'")
}
else println(db[db.lastIndex])
}
 
fun printAll() {
val db = load()
if (db.isEmpty()) {
println("No entries in database.")
return
}
// no need to sort db as items are added chronologically
for (item in db) println(item)
}
 
fun load(): MutableList<Item> {
val db = mutableListOf<Item>()
try {
file.forEachLine { line ->
val item = line.split(", ")
db.add(Item(item[0], item[1], item[2]))
}
}
catch (e: IOException) {
println(e)
System.exit(1)
}
return db
}
 
fun store(item: Item) {
try {
file.appendText("$item\n")
}
catch (e: IOException) {
println(e)
}
}
 
fun printUsage() {
println("""
|Usage:
| simdb cmd [categoryName]
| add add item, followed by optional category
| latest print last added item(s), followed by optional category
| all print all
| For instance: add "some item name" "some category name"
""".trimMargin())
}
 
fun main(args: Array<String>) {
if (args.size !in 1..3) {
printUsage()
return
}
file.createNewFile() // create file if it doesn't already exist
when (args[0].toLowerCase()) {
"add" -> addItem(args)
"latest" -> printLatest(args)
"all" -> printAll()
else -> printUsage()
}
}</syntaxhighlight>
 
{{out}}
Sample session.
<pre>
$ java -jar SimpleDatabase.jar add item1
$ java -jar SimpleDatabase.jar add item2
$ java -jar SimpleDatabase.jar add item3 cat3
$ java -jar SimpleDatabase.jar add item4 cat3
$ java -jar SimpleDatabase.jar add item5 cat3
$ java -jar SimpleDatabase.jar latest
item5, 2018-03-23 16:49:46, cat3
$ java -jar SimpleDatabase.jar latest none
item2, 2018-03-23 16:49:28, none
$ java -jar SimpleDatabase.jar latest cat4
There are no items for category 'cat4'
$ java -jar SimpleDatabase.jar all
item1, 2018-03-23 16:49:25, none
item2, 2018-03-23 16:49:28, none
item3, 2018-03-23 16:49:34, cat3
item4, 2018-03-23 16:49:40, cat3
item5, 2018-03-23 16:49:46, cat3
</pre>
 
=={{header|M2000 Interpreter}}==
Write the code on a UTF-8 text file as tool.gsb
 
Assign gsb files to open with M2000.exe (the M2000 environment)
 
Open the folder where exist tool.gsb in a cmd window
 
then follow the > lines in the out session
 
The format of file is xml, Utf8 with a BOM.
 
The M2000 environment not used here, all the output redirect to console. (Although the environment is a Window program, we can attach the console).
 
 
<syntaxhighlight lang="m2000 interpreter">
MODULE GLOBAL interpret {
global filename$="base1.xml"
module latest {
PrintConsoleLn("The latest entry is:")
if exist(filename$) else exit
declare xml xmlData
with xml, "xml" as doc$, "beautify" as beautify
doc$=string$(eval$(buffer(filename$)) as UTF8dec)
with xml, "lastchild" set child
with child,"attr" as attr$()
PrintConsoleLn(attr$("name")+","+@tag$()+","+attr$("date"))
declare xml nothing
}
module latestForEachTag {
PrintConsoleLn("latest entry for each tag:")
if exist(filename$) else exit
declare xml xmlData
with xml, "xml" as doc$, "beautify" as beautify
doc$=string$(eval$(buffer("base1.xml")) as UTF8dec)
with xml, "firstchild" as firstchild
child=firstchild
with child,"attr" as attr$()
inventory alfa
do
if not exist(alfa, @tag$()) then
append alfa, @tag$():=child
else
return alfa, @tag$():=child
end if
Method xml, "EndOffChilds", &child as ok
when ok
sort alfa
k=each(alfa)
while k
child=eval(k)
PrintConsoleLn(attr$("name")+","+@tag$()+","+attr$("date"))
end while
declare xml nothing
}
module All {
PrintConsoleLn("All entries sorted by date:")
if exist(filename$) else exit
declare xml xmlData
with xml, "xml" as doc$, "beautify" as beautify
doc$=string$(eval$(buffer("base1.xml")) as UTF8dec)
with xml, "firstchild" as firstchild
child=firstchild
with child,"attr" as attr$()
inventory alfa
i=0
do
// prevent same keys using a unique patch key
append alfa, attr$("date")+str$(i,"000000"):=child
i++
Method xml, "EndOffChilds", &child as ok
when ok
sort alfa
k=each(alfa)
while k
child=eval(k)
PrintConsoleLn(attr$("name")+","+@tag$()+","+attr$("date"))
end while
declare xml nothing
}
module add (line$) {
line$=trim$(line$)
if line$="" then exit
declare xml xmlData
with xml, "xml" as doc$, "beautify" as beautify
bom$=str$(format$("\uef\ubb\ubf"))
// len(bom$)=1.5 (1.5*2=3 bytes)
k=0
if exist(filename$) then try {k=filelen(filename$)}
if k<10 then
method xml, "PrepareNodeSimple", "xml" as ProcessInstructions
method xml, "PlaceAttributeToNode", ProcessInstructions, "version", "1.0"
method xml, "PlaceAttributeToNode", ProcessInstructions, "encoding", "utf-8-sig"
method xml, "PlaceProcessingInstructions", ProcessInstructions
method xml, "PrepareNode", "MyFile" as Node
method xml, "InsertNode", Node
else
doc$=string$(eval$(buffer(filename$)) as UTF8dec)
end if
a$=""""+line$
def name$, tag$,date$
do
a$=rightpart$(a$, """") : what$=lcase$(trim$(leftpart$(a$, """")))
if what$="" then exit
a$=rightpart$(a$, """") :par$=leftpart$(a$, """")
select case what$
case "name"
name$=par$
case "tag"
tag$=par$
case "date"
date$=par$
end select
always
if name$<>"" and date$<>"" then
method xml, "PrepareNode", "Row", "" as Node1
method xml, "PlaceAttributeToNode", Node1, "name", name$
if tag$<>"" then method xml, "PlaceAttributeToNode", Node1, "tag", tag$
method xml, "PlaceAttributeToNode", Node1, "date", date$
method xml, "AppendChild", Node1
open filename$ for wide output as #f
print #f, bom$;string$(doc$ as UTF8enc);
close #f
beautify=-4
PrintConsoleLn(doc$)
end if
declare xml nothing
}
declare FreeConsole lib "Kernel32.FreeConsole"
declare GetStdHandle lib "Kernel32.GetStdHandle" {long a}
declare AttachConsole lib "Kernel32.AttachConsole" {long a}
declare CloseHandle lib "Kernel32.CloseHandle" {long a}
declare global WriteCons Lib "Kernel32.WriteConsoleW" {long cons, a$, long n, Long p, long u}
long STD_OUTPUT_HANDLE=-11
global retvalue
buffer clear retvalue as long
ret=AttachConsole(-1)
global m=GetStdHandle(STD_OUTPUT_HANDLE)
if ret=0 then beep: exit
if not islet then
try {
open "tool.bat" for output as #f
print #f, {@}+appdir$+{m2000.exe data {%*}: dir %cd%:load tool
}
close #f
}
PrintConsoleLn("")
dos "tool.bat"
else
read cmd$
cmd$=trim$(cmd$)+" "
select case lcase$(leftpart$(cmd$, " "))
case "add"
add rightpart$(cmd$," ")
case "latest"
latest
case "latest-per-tag"
latestForEachTag
case "all-entries"
all
case else
help()
end select
end if
call void closehandle(m)
call void freeconsole()
 
Sub PrintConsole(a$)
Call Void WriteCons(m, a$, Len(a$), retvalue(0), 0)
End Sub
Sub PrintConsoleLn(a$)
a$+={
}
Call Void WriteCons(m, a$, Len(a$), retvalue(0), 0)
End Sub
// function is static here but can be called from child modules, because there are in the same block of code
// although attr$() must defined in each module. (scope constrain to module block, for local identifiers).
function tag$()
try { // if no tag exist error raised
=attr$("tag")
}
end function
Sub Help()
h$={Commands:
tool add name "anyname" tag "tagtext" date "YYYY.MM.DD.HH:MM"
tool latest
tool latest-per-tag
tool all-entries
}
PrintConsole(h$)
End Sub
}
module interpret1 {
try {interpret}
}
interpret1: end
</syntaxhighlight>
{{out}}
<pre>
first time the program make a tool.bat
>tool.gsb
 
So now we can call the tool bat.
>tool
Commands:
tool add name "anyname" tag "tagtext" date "YYYY.MM.DD.HH:MM"
tool latest
tool latest-per-tag
tool all-entries
 
>tool add name "BOB" tag "EAT A LOT" date "2022.10.21.04:00"
>tool add name "JOHN" tag "DRINK WATER" "date 2022.10.15.12:00"
>tool add name "PAUL" tag "EAT A LOT" date "2022.10.13.22:00"
>tool add name "SUZAN" tag "DRINK WATER" date "2022.10.13.12:00"
>tool add name "PHILIP" tag "DRINK WATER" date "2022.10.13.10:00"
>tool add name "MONDY" tag "EAT A LOT" date "2022.10.10.12:00"
>tool add name "MARY" tag "PIZZA FRIENDLY" date "2022.10.10.12:00"
>tool add name "DONALD" tag "PIZZA FRIENDLY" date "2022.10.10.02:00"
>tool add name "GEORGE" date "2022.11.29.16:55"
 
This is the last print from last tool add:
<?xml version="1.0" encoding="utf-8-sig"?>
<MyFile>
<Row name="BOB" tag="EAT A LOT" date="2022.10.21.04:00"></Row>
<Row name="PAUL" tag="EAT A LOT" date="2022.10.13.22:00"></Row>
<Row name="SUZAN" tag="DRINK WATER" date="2022.10.13.12:00"></Row>
<Row name="PHILIP" tag="DRINK WATER" date="2022.10.13.10:00"></Row>
<Row name="MONDY" tag="EAT A LOT" date="2022.10.10.12:00"></Row>
<Row name="MARY" tag="PIZZA FRIENDLY" date="2022.10.10.12:00"></Row>
<Row name="DONALD" tag="PIZZA FRIENDLY" date="2022.10.10.02:00"></Row>
<Row name="GEORGE" date="2022.11.29.16:55"></Row>
</MyFile>
 
 
>tool latest
The latest entry is:
GEORGE,,2022.11.29.16:55
 
>tool latest-per-tag
latest entry for each tag:
GEORGE,,2022.11.29.16:55
PHILIP,DRINK WATER,2022.10.13.10:00
MONDY,EAT A LOT,2022.10.10.12:00
DONALD,PIZZA FRIENDLY,2022.10.10.02:00
 
>tool all-entries
All entries sorted by date:
DONALD,PIZZA FRIENDLY,2022.10.10.02:00
MONDY,EAT A LOT,2022.10.10.12:00
MARY,PIZZA FRIENDLY,2022.10.10.12:00
PHILIP,DRINK WATER,2022.10.13.10:00
SUZAN,DRINK WATER,2022.10.13.12:00
PAUL,EAT A LOT,2022.10.13.22:00
BOB,EAT A LOT,2022.10.21.04:00
GEORGE,,2022.11.29.16:55
</pre>
 
=={{header|Nim}}==
{{trans|D}}
{{trans|Kotlin}}
There are some important differences with D version and Kotlin versions. Firstly, the way to manage the command arguments is somewhat different. And secondly, the database is stored in JSON format rather than in CSV format. Indeed, if Nim provides a parser of CSV files, it provides better support for JSON with procedures for serialization of Nim objects to JSON and deserialization from JSON to Nim objects. This can be seen in the following program.
 
<syntaxhighlight lang="nim">import algorithm, json, os, strformat, strutils, times
 
const FileName = "simdb.json"
 
type
 
Item = object
name: string
date: string
category: string
 
Database = seq[Item]
 
DbError = object of CatchableError
 
 
proc load(): Database =
if fileExists(FileName):
let node = try: FileName.parseFile()
except JsonParsingError:
raise newException(DbError, getCurrentExceptionMsg())
result = node.to(DataBase)
 
 
proc store(db: Database) =
try:
FileName.writeFile $(%* db)
except IOError:
quit "Unable to save database.", QuitFailure
 
 
proc addItem(args: seq[string]) =
var db = try: load()
except DbError: quit getCurrentExceptionMsg(), QuitFailure
 
let date = now().format("yyyy-MM-dd HH:mm:ss")
let cat = if args.len == 2: args[1] else: "none"
db.add Item(name: args[0], date: date, category: cat)
db.store()
 
 
proc printLatest(args: seq[string]) =
let db = try: load()
except DbError: quit getCurrentExceptionMsg(), QuitFailure
if db.len == 0:
echo "No entries in database."
return
 
# No need to sort db as items are added chronologically.
if args.len == 1:
var found = false
for item in reversed(db):
if item.category == args[0]:
echo item
found = true
break
if not found:
echo &"There are no items for category '{args[0]}'"
else:
echo db[^1]
 
 
proc printAll() =
let db = try: load()
except DbError: quit getCurrentExceptionMsg(), QuitFailure
if db.len == 0:
echo "No entries in database."
return
for item in db:
echo item
 
 
proc printUsage() =
echo &"""
Usage:
{getAppFilename().splitPath().tail} cmd [categoryName]
 
add add item, followed by optional category
latest print last added item(s), followed by optional category
all print all
 
For instance: add "some item name" "some category name"
"""
quit QuitFailure
 
 
if paramCount() notin 1..3: printUsage()
 
var params = commandLineParams()
let command = params[0].toLowerAscii
params.delete(0)
case command
of "add":
if params.len == 0: printUsage()
addItem(params)
of "latest":
if params.len > 1: printUsage()
printLatest(params)
of "all":
if params.len != 0: printUsage()
printAll()</syntaxhighlight>
 
{{out}}
Sample session (same as that of Kotlin).
<pre>$ ./simple_database add item1
$ ./simple_database add item2
$ ./simple_database add item3 cat3
$ ./simple_database add item4 cat3
$ ./simple_database add item5 cat3
$ ./simple_database latest
(name: "item5", date: "2021-04-09 00:31:34", category: "cat3")
$ ./simple_database latest none
(name: "item2", date: "2021-04-09 00:31:08", category: "none")
$ ./simple_database latest cat4
There are no items for category 'cat4'
$ ./simple_database all
(name: "item1", date: "2021-04-09 00:31:03", category: "none")
(name: "item2", date: "2021-04-09 00:31:08", category: "none")
(name: "item3", date: "2021-04-09 00:31:19", category: "cat3")
(name: "item4", date: "2021-04-09 00:31:25", category: "cat3")
(name: "item5", date: "2021-04-09 00:31:34", category: "cat3")</pre>
 
=={{header|Perl}}==
<syntaxhighlight lang="perl">#!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };
 
use JSON::PP;
use Time::Piece;
 
use constant {
NAME => 0,
CATEGORY => 1,
DATE => 2,
DB => 'simple-db',
};
 
my $operation = shift // "";
 
my %dispatch = (
n => \&add_new,
l => \&print_latest,
L => \&print_latest_for_categories,
a => \&print_all,
);
 
if ($dispatch{$operation}) {
$dispatch{$operation}->(@ARGV);
} else {
die "Invalid option. Use one of n, l, L, a.\n"
}
 
sub add_new {
my ($name, $category, $date) = @_;
my $db = eval { load() } || {};
if (defined $date) {
eval { 'Time::Piece'->strptime($date, '%Y-%m-%d'); 1 }
or die "Invalid date format: YYYY-MM-DD.\n";
 
} else {
$date //= localtime->ymd;
}
 
my @ids = keys %{ $db->{by_id} };
my $max_id = max(num => @ids) || 0;
$db->{by_id}{ ++$max_id } = [ $name, $category, $date ];
save($db);
}
 
sub print_latest {
build_indexes( my $db = load(), 0, 1 );
_print_latest($db);
}
 
sub _print_latest {
my ($db, $category) = @_;
my @dates = keys %{ $db->{by_date} };
@dates = grep {
grep $db->{by_id}{$_}[CATEGORY] eq $category,
@{ $db->{by_date}{$_} };
} @dates if defined $category;
 
my $last_date = max(str => @dates);
say for map $db->{by_id}{$_}[NAME],
grep ! defined $category
|| $db->{by_id}{$_}[CATEGORY] eq $category,
@{ $db->{by_date}{$last_date} };
}
 
sub max {
my $type = shift;
my $max = $_[0];
{ num => sub { $_ > $max },
str => sub { $_ gt $max},
}->{$type}->() and $max = $_
for @_[ 1 .. $#_ ];
return $max
}
 
sub print_latest_for_categories {
build_indexes( my $db = load(), 1, 1 );
 
for my $category (sort keys %{ $db->{by_category} }){
say "* $category";
_print_latest($db, $category);
}
}
 
sub print_all {
build_indexes( my $db = load(), 0, 1 );
 
for my $date (sort keys %{ $db->{by_date} }) {
for my $id (@{ $db->{by_date}{$date} }) {
say $db->{by_id}{$id}[NAME];
}
}
}
 
sub load {
open my $in, '<', DB or die "Can't open database: $!\n";
local $/;
return { by_id => decode_json(<$in>) };
}
 
sub save {
my ($db) = @_;
open my $out, '>', DB or die "Can't save database: $!\n";
print {$out} encode_json($db->{by_id});
close $out;
}
 
sub build_indexes {
my ($db, $by_category, $by_date) = @_;
for my $id (keys %{ $db->{by_id} }) {
push @{ $db->{by_category}{ $db->{by_id}{$id}[CATEGORY] } }, $id
if $by_category;
push @{ $db->{by_date}{ $db->{by_id}{$id}[DATE] } }, $id
if $by_date;
}
}</syntaxhighlight>
Sample session<pre> ~ $ db.pl n 'Donald Trump' Republican 2017-01-20
~ $ db.pl n 'Barack Obama' Democratic 2009-01-20
~ $ db.pl n 'Bill Clinton' Democratic 1993-01-20
~ $ db.pl n 'George W. Bush' Republican 2001-01-20
~ $ db.pl a
Bill Clinton
George W. Bush
Barack Obama
Donald Trump
~ $ db.pl l
Donald Trump
~ $ db.pl L
* Democratic
Barack Obama
* Republican
Donald Trump</pre>
 
=={{header|Phix}}==
<!--<syntaxhighlight lang="phix">(notonline)-->
<span style="color: #000080;font-style:italic;">--
-- demo\rosetta\Simple_db.exw
-- ==========================
--</span>
<span style="color: #008080;">without</span> <span style="color: #008080;">js</span> <span style="color: #000080;font-style:italic;">-- (file i/o, gets(0), getenv)</span>
<span style="color: #008080;">include</span> <span style="color: #004080;">timedate</span><span style="color: #0000FF;">.</span><span style="color: #000000;">e</span>
<span style="color: #008080;">constant</span> <span style="color: #000000;">filename</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">getenv</span><span style="color: #0000FF;">(</span><span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">platform</span><span style="color: #0000FF;">()=</span><span style="color: #004600;">WINDOWS</span><span style="color: #0000FF;">?</span><span style="color: #008000;">"APPDATA"</span><span style="color: #0000FF;">:</span><span style="color: #008000;">"HOME"</span><span style="color: #0000FF;">))&</span><span style="color: #008000;">"/simple_db.csv"</span>
<span style="color: #008080;">procedure</span> <span style="color: #000000;">add</span><span style="color: #0000FF;">(</span><span style="color: #004080;">sequence</span> <span style="color: #000000;">cmd</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">if</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">cmd</span><span style="color: #0000FF;">)=</span><span style="color: #000000;">0</span>
<span style="color: #008080;">or</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">cmd</span><span style="color: #0000FF;">)></span><span style="color: #000000;">2</span> <span style="color: #008080;">then</span>
<span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"usage: add name [cat]\n"</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">else</span>
<span style="color: #004080;">string</span> <span style="color: #000000;">name</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">cmd</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">],</span>
<span style="color: #000000;">cat</span> <span style="color: #0000FF;">=</span> <span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">cmd</span><span style="color: #0000FF;">)=</span><span style="color: #000000;">2</span><span style="color: #0000FF;">?</span><span style="color: #000000;">cmd</span><span style="color: #0000FF;">[</span><span style="color: #000000;">2</span><span style="color: #0000FF;">]:</span><span style="color: #008000;">"none"</span><span style="color: #0000FF;">)</span>
<span style="color: #000000;">datestr</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">format_timedate</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">date</span><span style="color: #0000FF;">(),</span><span style="color: #008000;">"YYYY/MM/DD h:mmpm"</span><span style="color: #0000FF;">)</span>
<span style="color: #004080;">integer</span> <span style="color: #000000;">fn</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">open</span><span style="color: #0000FF;">(</span><span style="color: #000000;">filename</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"a"</span><span style="color: #0000FF;">)</span>
<span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">fn</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"%s,%s,%s\n"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">name</span><span style="color: #0000FF;">,</span><span style="color: #000000;">cat</span><span style="color: #0000FF;">,</span><span style="color: #000000;">datestr</span><span style="color: #0000FF;">})</span>
<span style="color: #7060A8;">close</span><span style="color: #0000FF;">(</span><span style="color: #000000;">fn</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">procedure</span>
<span style="color: #008080;">procedure</span> <span style="color: #000000;">last</span><span style="color: #0000FF;">(</span><span style="color: #004080;">sequence</span> <span style="color: #000000;">cmd</span><span style="color: #0000FF;">)</span>
<span style="color: #004080;">integer</span> <span style="color: #000000;">fn</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">open</span><span style="color: #0000FF;">(</span><span style="color: #000000;">filename</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"r"</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">fn</span><span style="color: #0000FF;">=-</span><span style="color: #000000;">1</span> <span style="color: #008080;">then</span>
<span style="color: #7060A8;">puts</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"file not found\n"</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">return</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #004080;">integer</span> <span style="color: #000000;">lc</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">cmd</span><span style="color: #0000FF;">)</span>
<span style="color: #004080;">string</span> <span style="color: #000000;">last</span> <span style="color: #0000FF;">=</span> <span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #000000;">lc</span><span style="color: #0000FF;">?</span><span style="color: #008000;">"&lt;no entries for that category&gt;\n"</span><span style="color: #0000FF;">:</span><span style="color: #008000;">"&lt;empty&gt;\n"</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">while</span> <span style="color: #000000;">1</span> <span style="color: #008080;">do</span>
<span style="color: #004080;">object</span> <span style="color: #000000;">line</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">gets</span><span style="color: #0000FF;">(</span><span style="color: #000000;">fn</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">if</span> <span style="color: #004080;">atom</span><span style="color: #0000FF;">(</span><span style="color: #000000;">line</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">then</span> <span style="color: #008080;">exit</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">lc</span><span style="color: #0000FF;">=</span><span style="color: #000000;">0</span> <span style="color: #008080;">or</span> <span style="color: #7060A8;">split</span><span style="color: #0000FF;">(</span><span style="color: #000000;">line</span><span style="color: #0000FF;">,</span><span style="color: #008000;">','</span><span style="color: #0000FF;">)[</span><span style="color: #000000;">2</span><span style="color: #0000FF;">]=</span><span style="color: #000000;">cmd</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]</span> <span style="color: #008080;">then</span>
<span style="color: #000000;">last</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">line</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
<span style="color: #7060A8;">puts</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #000000;">last</span><span style="color: #0000FF;">)</span>
<span style="color: #7060A8;">close</span><span style="color: #0000FF;">(</span><span style="color: #000000;">fn</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">procedure</span>
<span style="color: #004080;">sequence</span> <span style="color: #000000;">dates</span>
<span style="color: #008080;">function</span> <span style="color: #000000;">by_date</span><span style="color: #0000FF;">(</span><span style="color: #004080;">integer</span> <span style="color: #000000;">d1</span><span style="color: #0000FF;">,</span> <span style="color: #004080;">integer</span> <span style="color: #000000;">d2</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">return</span> <span style="color: #7060A8;">compare</span><span style="color: #0000FF;">(</span><span style="color: #000000;">dates</span><span style="color: #0000FF;">[</span><span style="color: #000000;">d1</span><span style="color: #0000FF;">],</span><span style="color: #000000;">dates</span><span style="color: #0000FF;">[</span><span style="color: #000000;">d2</span><span style="color: #0000FF;">])</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
<span style="color: #008080;">procedure</span> <span style="color: #000000;">sort_by_date</span><span style="color: #0000FF;">()</span>
<span style="color: #000080;font-style:italic;">-- (simple_db.csv should be edited manually to prove the date sort works)</span>
<span style="color: #004080;">integer</span> <span style="color: #000000;">fn</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">open</span><span style="color: #0000FF;">(</span><span style="color: #000000;">filename</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"r"</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">fn</span><span style="color: #0000FF;">=-</span><span style="color: #000000;">1</span> <span style="color: #008080;">then</span>
<span style="color: #7060A8;">puts</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"file not found\n"</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">return</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #004080;">sequence</span> <span style="color: #000000;">lines</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{}</span>
<span style="color: #000000;">dates</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{}</span>
<span style="color: #008080;">while</span> <span style="color: #000000;">1</span> <span style="color: #008080;">do</span>
<span style="color: #004080;">object</span> <span style="color: #000000;">line</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">gets</span><span style="color: #0000FF;">(</span><span style="color: #000000;">fn</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">if</span> <span style="color: #004080;">atom</span><span style="color: #0000FF;">(</span><span style="color: #000000;">line</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">then</span> <span style="color: #008080;">exit</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #000000;">lines</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">append</span><span style="color: #0000FF;">(</span><span style="color: #000000;">lines</span><span style="color: #0000FF;">,</span><span style="color: #000000;">line</span><span style="color: #0000FF;">)</span>
<span style="color: #000000;">dates</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">append</span><span style="color: #0000FF;">(</span><span style="color: #000000;">dates</span><span style="color: #0000FF;">,</span><span style="color: #7060A8;">split</span><span style="color: #0000FF;">(</span><span style="color: #000000;">line</span><span style="color: #0000FF;">,</span><span style="color: #008000;">','</span><span style="color: #0000FF;">)[</span><span style="color: #000000;">3</span><span style="color: #0000FF;">])</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
<span style="color: #7060A8;">close</span><span style="color: #0000FF;">(</span><span style="color: #000000;">fn</span><span style="color: #0000FF;">)</span>
<span style="color: #004080;">sequence</span> <span style="color: #000000;">tags</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">custom_sort</span><span style="color: #0000FF;">(</span><span style="color: #000000;">by_date</span><span style="color: #0000FF;">,</span><span style="color: #7060A8;">tagset</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">lines</span><span style="color: #0000FF;">)))</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">tags</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">do</span>
<span style="color: #7060A8;">puts</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #000000;">lines</span><span style="color: #0000FF;">[</span><span style="color: #000000;">tags</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]])</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">procedure</span>
<span style="color: #008080;">procedure</span> <span style="color: #000000;">process</span><span style="color: #0000FF;">(</span><span style="color: #004080;">sequence</span> <span style="color: #000000;">cmd</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">switch</span> <span style="color: #000000;">cmd</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]</span> <span style="color: #008080;">do</span>
<span style="color: #008080;">case</span> <span style="color: #008000;">"add"</span><span style="color: #0000FF;">:</span> <span style="color: #000000;">add</span><span style="color: #0000FF;">(</span><span style="color: #000000;">cmd</span><span style="color: #0000FF;">[</span><span style="color: #000000;">2</span><span style="color: #0000FF;">..$])</span>
<span style="color: #008080;">case</span> <span style="color: #008000;">"last"</span><span style="color: #0000FF;">:</span> <span style="color: #000000;">last</span><span style="color: #0000FF;">(</span><span style="color: #000000;">cmd</span><span style="color: #0000FF;">[</span><span style="color: #000000;">2</span><span style="color: #0000FF;">..$])</span>
<span style="color: #008080;">case</span> <span style="color: #008000;">"sort"</span><span style="color: #0000FF;">:</span> <span style="color: #000000;">sort_by_date</span><span style="color: #0000FF;">()</span>
<span style="color: #008080;">default</span><span style="color: #0000FF;">:</span> <span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"unknown command: %s\n"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">cmd</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]})</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">switch</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">procedure</span>
<span style="color: #008080;">constant</span> <span style="color: #000000;">helptext</span> <span style="color: #0000FF;">=</span> <span style="color: #008000;">"""
p demo\rosetta\Simple_db -- interactive mode, commands as below
p demo\rosetta\Simple_db add name [cat] -- add entry
p demo\rosetta\Simple_db last [cat] -- show last entry [in specified category]
p demo\rosetta\Simple_db sort -- show full list sorted by date
"""</span>
<span style="color: #004080;">sequence</span> <span style="color: #000000;">cl</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">command_line</span><span style="color: #0000FF;">()</span>
<span style="color: #008080;">if</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">cl</span><span style="color: #0000FF;">)<</span><span style="color: #000000;">3</span> <span style="color: #008080;">then</span>
<span style="color: #000080;font-style:italic;">-- interactive mode</span>
<span style="color: #7060A8;">puts</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #000000;">helptext</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">while</span> <span style="color: #000000;">1</span> <span style="color: #008080;">do</span>
<span style="color: #7060A8;">puts</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"&gt;"</span><span style="color: #0000FF;">)</span>
<span style="color: #004080;">object</span> <span style="color: #000000;">line</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">trim</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">gets</span><span style="color: #0000FF;">(</span><span style="color: #000000;">0</span><span style="color: #0000FF;">))</span>
<span style="color: #008080;">if</span> <span style="color: #004080;">atom</span><span style="color: #0000FF;">(</span><span style="color: #000000;">line</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">or</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">line</span><span style="color: #0000FF;">)=</span><span style="color: #000000;">0</span> <span style="color: #008080;">then</span> <span style="color: #008080;">exit</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #7060A8;">puts</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"\n"</span><span style="color: #0000FF;">)</span>
<span style="color: #000000;">process</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">split</span><span style="color: #0000FF;">(</span><span style="color: #000000;">line</span><span style="color: #0000FF;">))</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
<span style="color: #008080;">else</span>
<span style="color: #000000;">process</span><span style="color: #0000FF;">(</span><span style="color: #000000;">cl</span><span style="color: #0000FF;">[</span><span style="color: #000000;">3</span><span style="color: #0000FF;">..$])</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<!--</syntaxhighlight>-->
Sample session
<pre>
C:\Program Files (x86)\Phix>p demo\rosetta\simple_db
p demo\rosetta\Simple_db -- interactive mode, commands as below
p demo\rosetta\Simple_db add name [cat] -- add entry
p demo\rosetta\Simple_db last [cat] -- show last entry [in specified category]
p demo\rosetta\Simple_db sort -- show full list sorted by date
>sort
fred,none,2016/07/25 12:30pm
cliff,none,2016/07/25 12:31pm
barney,none,2016/07/25 12:32pm
one,two,2016/07/25 12:33pm
>add three four
>sort
fred,none,2016/07/25 12:30pm
cliff,none,2016/07/25 12:31pm
barney,none,2016/07/25 12:32pm
one,two,2016/07/25 12:33pm
three,four,2016/07/25 12:39pm
>last
three,four,2016/07/25 12:39pm
>last one
<no entries for that category>
>last two
one,two,2016/07/25 12:33pm
>
</pre>
 
=={{header|PicoLisp}}==
The '[http://software-lab.de/doc/refR.html#rc rc]' resource file handling function is used typically for such tasks. It also takes care of proper locking and protection.
<syntaxhighlight lang="picolisp">#!/usr/bin/pil
 
(de usage ()
(prinl
"Usage:^J\
sdb <file> add <title> <cat> <date> ... Add a new entry^J\
sdb <file> get <title> Retrieve an entry^J\
sdb <file> latest Print the latest entry^J\
sdb <file> categories Print the latest for each cat^J\
sdb <file> Print all, sorted by date" ) )
 
(de printEntry (E)
(apply println (cdddr E) (car E) (cadr E) (datStr (caddr E))) )
 
(ifn (setq *File (opt))
(usage)
(case (opt)
(add
(let (Ttl (opt) Cat (opt))
(if (strDat (opt))
(rc *File Ttl (cons Cat @ (argv)))
(prinl "Bad date") ) ) )
(get
(let Ttl (opt)
(when (rc *File Ttl)
(printEntry (cons Ttl @)) ) ) )
(latest
(printEntry (maxi caddr (in *File (read)))) )
(categories
(for Cat (by cadr group (in *File (read)))
(printEntry (maxi caddr Cat)) ) )
(NIL
(mapc printEntry (by caddr sort (in *File (read)))) )
(T (usage)) ) )
 
(bye)</syntaxhighlight>
Test:
<pre>$ sdb CDs add "Title 1" "Category 1" 2011-11-13
$ sdb CDs add "Title 2" "Category 2" 2011-11-12
$ sdb CDs add "Title 3" "Category 1" 2011-11-14 foo bar
$ sdb CDs add "Title 4" "Category 2" 2011-11-15 mumble
 
$ sdb CDs get "Title 3"
"Title 3" "Category 1" "2011-11-14" "foo" "bar"
 
$ sdb CDs latest
"Title 4" "Category 2" "2011-11-15" "mumble"
 
$ sdb CDs categories
"Title 4" "Category 2" "2011-11-15" "mumble"
"Title 3" "Category 1" "2011-11-14" "foo" "bar"
 
$ sdb CDs
"Title 2" "Category 2" "2011-11-12"
"Title 1" "Category 1" "2011-11-13"
"Title 3" "Category 1" "2011-11-14" "foo" "bar"
"Title 4" "Category 2" "2011-11-15" "mumble"</pre>
 
=={{header|Pike}}==
{{trans|Common Lisp}} (simplified)
<syntaxhighlight lang="pike">mapping db = ([]);
 
mapping make_episode(string series, string title, string episode, array date)
{
return ([ "series":series, "episode":episode, "title":title, "date":date ]);
}
 
void print_episode(mapping episode)
{
write(" %-30s %10s %-30s (%{%d.%})\n",
episode->series, episode->episode, episode->title, episode->date);
}
 
void print_series(mapping series)
{
write("%-30s %-10s\n", series->series, series->status);
map(series->episodes, print_episode);
}
 
void dump_db(mapping database)
{
foreach(database; string name; mapping series)
{
print_series(series);
}
}
 
array get_latest(mapping database)
{
array latest = ({});
foreach(database; string name; mapping series)
{
latest += ({ series->episodes[0] });
}
return latest;
}
 
int(0..1) compare_date(array a, array b)
{
if (!arrayp(a) && !arrayp(b)) return false;
if (!arrayp(a) || !sizeof(a)) return arrayp(b) && sizeof(b);
if (!arrayp(b) || !sizeof(b)) return arrayp(a) && sizeof(a);
if (a[0] == b[0]) return compare_date(a[1..], b[1..]);
return a[0] < b[0];
}
 
int(0..1) compare_by_date(mapping a, mapping b)
{
return compare_date(reverse(a->date), reverse(b->date));
}
 
void watch_list(mapping database)
{
map(Array.sort_array(get_latest(database), compare_by_date),
print_episode);
}
 
string prompt_read(string prompt)
{
write("%s: ", prompt);
return Stdio.stdin.gets();
}
 
array parse_date(string date)
{
return (array(int))(date/".");
}
 
mapping prompt_for_episode()
{
return make_episode(prompt_read("Series"),
prompt_read("Title"),
prompt_read("Episode"),
parse_date(prompt_read("Date watched")));
}
 
// pike offers encode_value() and decode_value() as standard ways
// to save and read data, but that is not a human readable format.
// therefore we are instead printing the structure as debug-output
// which is a readable form as long as it only contains integers,
// strings, mappings, arrays and multisets this format can be read by pike.
// to read it we are creating a class that contains the data as a value,
// which is then compiled and instantiated to allow us to pull the data out.
void save_db(string filename, mapping database)
{
Stdio.write_file(filename, sprintf("%O", database));
}
 
void watch_save()
{
save_db("pwatch", db);
}
 
mapping load_db(string filename)
{
if (file_stat(filename))
return compile_string("mixed data = " +
Stdio.read_file(filename) + ";")()->data;
else return ([]);
}
 
mapping get_series(string name, mapping database)
{
return database[name];
}
 
array get_episode_list(string series, mapping database)
{
return database[series]->episodes;
}
 
void watch_new_series(string name, string status, mapping database)
{
database[name] = (["series":name, "status":status, "episodes":({}) ]);
}
 
mapping get_or_add_series(string name, mapping database)
{
if (!database[name])
{
string answer = prompt_read("Add new series? [y/n]: ");
if (answer == "y")
watch_new_series(name, "active", database);
}
return database[name];
}
 
void watch_add(mapping database)
{
mapping episode = prompt_for_episode();
string series_name = episode->series;
mapping series = get_or_add_series(series_name, database);
if (!series)
watch_add(database);
else
series->episodes = Array.unshift(series->episodes, episode);
}
 
void watch_load()
{
db = load_db("pwatch");
}
 
int main(int argc, array argv)
{
watch_load();
if (argc>1 && argv[1] == "add")
{
watch_add(db);
watch_save();
}
else
watch_list(db);
}</syntaxhighlight>
 
=={{header|PowerShell}}==
<syntaxhighlight lang="powershell">
function db
{
[CmdletBinding(DefaultParameterSetName="None")]
[OutputType([PSCustomObject])]
Param
(
[Parameter(Mandatory=$false,
Position=0,
ParameterSetName="Add a new entry")]
[string]
$Path = ".\SimpleDatabase.csv",
 
[Parameter(Mandatory=$true,
ParameterSetName="Add a new entry")]
[string]
$Name,
 
[Parameter(Mandatory=$true,
ParameterSetName="Add a new entry")]
[string]
$Category,
 
[Parameter(Mandatory=$true,
ParameterSetName="Add a new entry")]
[datetime]
$Birthday,
 
[Parameter(ParameterSetName="Print the latest entry")]
[switch]
$Latest,
 
[Parameter(ParameterSetName="Print the latest entry for each category")]
[switch]
$LatestByCategory,
 
[Parameter(ParameterSetName="Print all entries sorted by a date")]
[switch]
$SortedByDate
)
 
if (-not (Test-Path -Path $Path))
{
'"Name","Category","Birthday"' | Out-File -FilePath $Path
}
 
$db = Import-Csv -Path $Path | Foreach-Object {
$_.Birthday = $_.Birthday -as [datetime]
$_
}
 
switch ($PSCmdlet.ParameterSetName)
{
"Add a new entry"
{
[PSCustomObject]@{Name=$Name; Category=$Category; Birthday=$Birthday} | Export-Csv -Path $Path -Append
}
"Print the latest entry"
{
$db[-1]
}
"Print the latest entry for each category"
{
($db | Group-Object -Property Category).Name | ForEach-Object {($db | Where-Object -Property Category -Contains $_)[-1]}
}
"Print all entries sorted by a date"
{
$db | Sort-Object -Property Birthday
}
Default
{
$db
}
}
}
 
db -Name Bev -Category friend -Birthday 3/3/1983
db -Name Bob -Category family -Birthday 7/19/1987
db -Name Gill -Category friend -Birthday 12/9/1986
db -Name Gail -Category family -Birthday 2/11/1986
db -Name Vince -Category family -Birthday 3/10/1960
db -Name Wayne -Category coworker -Birthday 5/29/1962
</syntaxhighlight>
Here is the data from the CSV file as a PowerShell Object:
<syntaxhighlight lang="powershell">
db
</syntaxhighlight>
{{Out}}
<pre>
Name Category Birthday
---- -------- --------
Bev friend 3/3/1983 12:00:00 AM
Bob family 7/19/1987 12:00:00 AM
Gill friend 12/9/1986 12:00:00 AM
Gail family 2/11/1986 12:00:00 AM
Vince family 3/10/1960 12:00:00 AM
Wayne coworker 5/29/1962 12:00:00 AM
</pre>
The latest entry:
<syntaxhighlight lang="powershell">
db -Latest
</syntaxhighlight>
{{Out}}
<pre>
Name Category Birthday
---- -------- --------
Wayne coworker 5/29/1962 12:00:00 AM
</pre>
The latest entries by category:
<syntaxhighlight lang="powershell">
db -LatestByCategory
</syntaxhighlight>
{{Out}}
<pre>
Name Category Birthday
---- -------- --------
Gill friend 12/9/1986 12:00:00 AM
Vince family 3/10/1960 12:00:00 AM
Wayne coworker 5/29/1962 12:00:00 AM
</pre>
The database sorted on the Birthday property:
<syntaxhighlight lang="powershell">
db -SortedByDate
</syntaxhighlight>
{{Out}}
<pre>
Name Category Birthday
---- -------- --------
Vince family 3/10/1960 12:00:00 AM
Wayne coworker 5/29/1962 12:00:00 AM
Bev friend 3/3/1983 12:00:00 AM
Gail family 2/11/1986 12:00:00 AM
Gill friend 12/9/1986 12:00:00 AM
Bob family 7/19/1987 12:00:00 AM
</pre>
 
=={{header|Python}}==
<syntaxhighlight lang="python">#!/usr/bin/python3
 
'''\
Simple database for: http://rosettacode.org/wiki/Simple_database
 
'''
 
import argparse
from argparse import Namespace
import datetime
import shlex
 
 
def parse_args():
'Set up, parse, and return arguments'
parser = argparse.ArgumentParser(epilog=globals()['__doc__'])
 
parser.add_argument('command', choices='add pl plc pa'.split(),
help='''\
add: Add a new entry
pl: Print the latest entry
plc: Print the latest entry for each category/tag
pa: Print all entries sorted by a date''')
parser.add_argument('-d', '--description',
help='A description of the item. (e.g., title, name)')
parser.add_argument('-t', '--tag',
help=('''A category or tag (genre, topic, relationship '''
'''such as “friend” or “family”)'''))
parser.add_argument('-f', '--field', nargs=2, action='append',
help='Other optional fields with value (can be repeated)')
 
return parser
 
def do_add(args, dbname):
'Add a new entry'
if args.description is None:
args.description = ''
if args.tag is None:
args.tag = ''
del args.command
print('Writing record to %s' % dbname)
with open(dbname, 'a') as db:
db.write('%r\n' % args)
def do_pl(args, dbname):
'Print the latest entry'
print('Getting last record from %s' % dbname)
with open(dbname, 'r') as db:
for line in db: pass
record = eval(line)
del record._date
print(str(record))
def do_plc(args, dbname):
'Print the latest entry for each category/tag'
print('Getting latest record for each tag from %s' % dbname)
with open(dbname, 'r') as db:
records = [eval(line) for line in db]
tags = set(record.tag for record in records)
records.reverse()
for record in records:
if record.tag in tags:
del record._date
print(str(record))
tags.discard(record.tag)
if not tags: break
 
def do_pa(args, dbname):
'Print all entries sorted by a date'
print('Getting all records by date from %s' % dbname)
with open(dbname, 'r') as db:
records = [eval(line) for line in db]
for record in records:
del record._date
print(str(record))
 
def test():
import time
parser = parse_args()
for cmdline in [
"""-d Book -f title 'Windy places' -f type hardback --tag DISCOUNT add""",
"""-d Book -f title 'RC spammers' -f type paperback -t DISCOUNT add""",
"""-d Book -f title 'Splat it' -f type hardback -f special 'first edition' -t PREMIUM add""",
"""pl""",
"""plc""",
]:
args = parser.parse_args(shlex.split(cmdline))
now = datetime.datetime.utcnow()
args._date = now.isoformat()
do_command[args.command](args, dbname)
time.sleep(0.5)
 
 
do_command = dict(add=do_add, pl=do_pl, plc=do_plc, pa=do_pa)
dbname = '_simple_db_db.py'
 
 
if __name__ == '__main__':
if 0:
test()
else:
parser = parse_args()
args = parser.parse_args()
now = datetime.datetime.utcnow()
args._date = now.isoformat()
do_command[args.command](args, dbname)</syntaxhighlight>
 
;Sample session (Unix):
<pre>paddy3118:~$ ./simple_db.py -h
usage: simple_db.py [-h] [-d DESCRIPTION] [-t TAG] [-f FIELD FIELD]
{add,pl,plc,pa}
 
positional arguments:
{add,pl,plc,pa} add: Add a new entry pl: Print the latest entry plc:
Print the latest entry for each category/tag pa: Print
all entries sorted by a date
 
optional arguments:
-h, --help show this help message and exit
-d DESCRIPTION, --description DESCRIPTION
A description of the item. (e.g., title, name)
-t TAG, --tag TAG A category or tag (genre, topic, relationship such as
“friend” or “family”)
-f FIELD FIELD, --field FIELD FIELD
Other optional fields with value (can be repeated)
 
Simple database for: http://rosettacode.org/wiki/Simple_database
paddy3118:~$ ./simple_db.py -d Book -f title 'Windy places' -f type hardback --tag DISCOUNT add
Writing record to _simple_db_db.py
paddy3118:~$ ./simple_db.py -d Book -f title 'RC spammers' -f type paperback -t DISCOUNT add
Writing record to _simple_db_db.py
paddy3118:~$ ./simple_db.py -d Book -f title 'Splat it' -f type hardback -f special 'first edition' -t PREMIUM add
Writing record to _simple_db_db.py
paddy3118:~$ ./simple_db.py pl
Getting last record from _simple_db_db.py
Namespace(description='Book', field=[['title', 'Splat it'], ['type', 'hardback'], ['special', 'first edition']], tag='PREMIUM')
paddy3118:~$ ./simple_db.py plc
Getting latest record for each tag from _simple_db_db.py
Namespace(description='Book', field=[['title', 'Splat it'], ['type', 'hardback'], ['special', 'first edition']], tag='PREMIUM')
Namespace(description='Book', field=[['title', 'RC spammers'], ['type', 'paperback']], tag='DISCOUNT')
paddy3118:~$ ./simple_db.py pa
Getting all records by date from _simple_db_db.py
Namespace(description='Book', field=[['title', 'Windy places'], ['type', 'hardback']], tag='DISCOUNT')
Namespace(description='Book', field=[['title', 'RC spammers'], ['type', 'paperback']], tag='DISCOUNT')
Namespace(description='Book', field=[['title', 'Splat it'], ['type', 'hardback'], ['special', 'first edition']], tag='PREMIUM')
paddy3118:~$
paddy3118:~$ cat _simple_db_db.py
Namespace(_date='2012-08-18T06:02:44.947091', description='Book', field=[['title', 'Windy places'], ['type', 'hardback']], tag='DISCOUNT')
Namespace(_date='2012-08-18T06:03:11.477429', description='Book', field=[['title', 'RC spammers'], ['type', 'paperback']], tag='DISCOUNT')
Namespace(_date='2012-08-18T06:03:34.319799', description='Book', field=[['title', 'Splat it'], ['type', 'hardback'], ['special', 'first edition']], tag='PREMIUM')
paddy3118:~$ </pre>
 
=={{header|Racket}}==
<syntaxhighlight lang="racket">
#!/usr/bin/env racket
#lang racket
 
(define (*write file data) ; write data in human readable format (sexpr/line)
(with-output-to-file file #:exists 'replace
(lambda () (for ([x data]) (printf "~s\n" x)))))
(define *read file->list) ; read our "human readable format"
 
(command-line
#:once-any
[("-a") file title category date "Add an entry"
(*write file `(,@(*read file) (,title ,category ,date)))]
[("-d") file title "Delete an entry (all matching)"
(*write file (filter-not (lambda (x) (equal? (car x) title)) (*read file)))]
[("-p") file mode "Print entries, mode = latest, latest/cat, all, by-date"
(define data (*read file))
(define (show item)
(match item [(list title cat date) (printf "[~a] ~a; ~a\n" cat title date)]))
(case (string->symbol mode)
[(all) (for-each show data)]
[(by-date) (for-each show (sort data string<? #:key cadr))]
[(latest) (show (last data))]
[(latest/cat)
(define (last/cat c) (for/last ([x data] #:when (equal? c (cadr x))) x))
(for-each (compose1 show last/cat) (remove-duplicates (map cadr data)))]
[else (error 'sdb "bad printout mode")])])
</syntaxhighlight>
 
Sample run:
<pre>
$ ./sdb -h
sdb [ <option> ... ]
where <option> is one of
/ -a <file> <title> <category> <date> : Add an entry
| -d <file> <title> : Delete an entry (all matching)
\ -p <file> <mode> : Print entries, mode = latest, latest/cat, all
--help, -h : Show this help
-- : Do not treat any remaining argument as a switch (at this level)
/|\ Brackets indicate mutually exclusive options.
Multiple single-letter switches can be combined after one `-'; for
example: `-h-' is the same as `-h --'
$ ./sdb -a Stuffs A-Book books 2013-01-01
$ ./sdb -a Stuffs Another-Book books 2013-01-02
$ ./sdb -a Stuffs Some-CD cds 2013-01-03
$ ./sdb -a Stuffs A-Bad-CD cds 2013-01-04
$ ./sdb -p Stuffs all
[books] A-Book; 2013-01-01
[books] Another-Book; 2013-01-02
[cds] Some-CD; 2013-01-03
[cds] A-Bad-CD; 2013-01-04
$ ./sdb -p Stuffs latest
[cds] A-Bad-CD; 2013-01-04
$ ./sdb -p Stuffs latest/cat
[books] Another-Book; 2013-01-02
[cds] A-Bad-CD; 2013-01-04
$ ./sdb -d Stuffs A-Bad-CD
$ ./sdb -p Stuffs by-date
[books] A-Book; 2013-01-01
[books] Another-Book; 2013-01-02
[cds] Some-CD; 2013-01-03
</pre>
 
=={{header|Raku}}==
(formerly Perl 6)
A generic client/server JSON database.<br>
<b>server.raku:</b>
<syntaxhighlight lang="raku" line>#!/usr/bin/env raku
use JSON::Fast ;
sub MAIN( :$server='0.0.0.0', :$port=3333, :$dbfile='db' ) {
my %db;
my %index;
my $dbdata = slurp "$dbfile.json" ;
my $indexdata = slurp "{$dbfile}_index.json" ;
%db = from-json($dbdata) if $dbdata ;
%index = from-json($indexdata) if $indexdata ;
react {
whenever IO::Socket::Async.listen( $server , $port ) -> $conn {
whenever $conn.Supply.lines -> $line {
my %response = 'status' => '' ;
my $msg = from-json $line ;
say $msg.perl ;
given $msg<function> {
when 'set' {
%db{ $msg<topic> } = $msg<message> ;
%response<status> = 'ok' ;
%index<last_> = $msg<topic> ;
for %index<keys_>.keys -> $key {
if $msg<message>{$key} {
%index<lastkey_>{ $key }{ $msg<message>{$key} } = $msg<topic> ;
%index<idx_>{ $key }{ $msg<message>{$key} }{ $msg<topic> } = 1 ;
}
}
spurt "$dbfile.json", to-json(%db);
spurt "{$dbfile}_index.json", to-json(%index);
}
when 'get' {
%response<topic> = $msg<topic> ;
%response<message> = %db{ $msg<topic> } ;
%response<status> = 'ok' ;
}
when 'dump' {
%response{'data'} = %db ;
%response<status> = 'ok' ;
}
when 'dumpindex' {
%response{'data'} = %index ;
%response<status> = 'ok' ;
}
when 'delete' {
%db{ $msg<topic> }:delete;
%response<status> = 'ok' ;
spurt "$dbfile.json", to-json(%db);
reindex();
}
when 'addindex' {
%response<status> = 'ok' ;
%index<keys_>{ $msg<key>} =1 ;
reindex();
}
when 'reportlast' {
%response{'data'} = %db{%index<last_>} ;
%response<status> = 'ok' ;
}
when 'reportlastindex' {
%response<key> = $msg<key> ;
for %index<lastkey_>{$msg<key>}.keys -> $value {
#%response{'data'}.push: %db{ %index<lastkey_>{ $msg<key> }{ $value } } ;
%response{'data'}{$value} = %db{ %index<lastkey_>{ $msg<key> }{ $value } } ;
}
%response<status> = 'ok' ;
}
when 'reportindex' {
%response<status> = 'ok' ;
for %index<idx_>{$msg<key>}.keys.sort -> $value {
for %index<idx_>{ $msg<key> }{ $value }.keys.sort -> $topic {
%response<data>.push: %db{ $topic } ;
#%response<data>{$value} = %db{ $topic } ;
}
}
}
when 'commit' {
spurt "$dbfile.json", to-json(%db);
spurt "{$dbfile}_index.json", to-json(%index);
%response<status> = 'ok' ;
}
default {
%response<status> = 'error';
%response<error> = 'no function or not supported';
}
}
$conn.print( to-json(%response, :!pretty) ~ "\n" ) ;
LAST { $conn.close ; }
QUIT { default { $conn.close ; say "oh no, $_";}}
CATCH { default { say .^name, ': ', .Str , " handled in $?LINE";}}
}
}
}
sub reindex {
%index<idx_>:delete;
for %db.keys -> $topic {
my $msg = %db{$topic} ;
for %index<keys_>.keys -> $key {
if $msg{$key} {
%index<idx_>{ $key }{ $msg{$key} }{ $topic } = 1 ;
}
}
}
spurt "{$dbfile}_index.json", to-json(%index) ;
}
}</syntaxhighlight>
<b>client.raku:</b>
<syntaxhighlight lang="raku" line>#!/usr/bin/env raku
use JSON::Fast ;
multi MAIN('set', $topic, $message='', :$server='localhost', :$port='3333', :$json='') {
my %msg = function => 'set' , topic=> $topic , message=> $message ;
%msg{"message"} = from-json( $json ) if $json ;
sendmsg( %msg , $server, $port) ;
}
multi MAIN('add', $topic, $json, :$server='localhost', :$port='3333' ) {
my %msg = function => 'set' , topic=> $topic;
%msg{"message"} = from-json( $json ) if $json ;
sendmsg( %msg , $server, $port) ;
}
multi MAIN('get', $topic, :$server='localhost', :$port='3333') {
my %msg = function => 'get' , topic=> $topic ;
sendmsg( %msg , $server, $port) ;
}
multi MAIN('delete', $topic, :$server='localhost', :$port='3333') {
my %msg = function => 'delete' , topic=> $topic ;
sendmsg( %msg , $server, $port) ;
}
multi MAIN('dump', :$server='localhost', :$port='3333') {
my %msg = function => 'dump' ;
sendmsg( %msg , $server, $port) ;
}
multi MAIN('addindex', $key, :$server='localhost', :$port='3333') {
my %msg = function => 'addindex', key => $key ;
sendmsg( %msg , $server, $port) ;
}
multi MAIN('reportindex', $key, :$server='localhost', :$port='3333') {
my %msg = function => 'reportindex', key => $key ;
sendmsg( %msg , $server, $port) ;
}
multi MAIN('reportlastindex', $key, :$server='localhost', :$port='3333') {
my %msg = function => 'reportlastindex', key => $key ;
sendmsg( %msg , $server, $port) ;
}
multi MAIN('reportlast', :$server='localhost', :$port='3333') {
my %msg = function => 'reportlast' ;
sendmsg( %msg , $server, $port) ;
}
sub sendmsg( %msg , $server, $port){
my $conn = await IO::Socket::Async.connect( $server , $port );
$conn.print: to-json( %msg,:!pretty)~"\n";
react {
whenever $conn.Supply -> $data {
print $data;
$conn.close;
}
}
}</syntaxhighlight>
Example:
<pre>./client.raku addindex constructor
./client.raku addindex date
 
./client.raku add 2007 '{"date":"2007-11-04","constructor":"Ducati","name":"Casey Stoner"}'
./client.raku add 2008 '{"date":"2008-10-26","constructor":"Yamaha","name":"Valentino Rossi"}'
./client.raku add 2009 '{"date":"2009-11-08","constructor":"Yamaha","name":"Valentino Rossi"}'
./client.raku add 2010 '{"date":"2010-11-17","constructor":"Yamaha","name":"Jorge Lorenzo"}'
./client.raku add 2011 '{"date":"2011-11-06","constructor":"Honda","name":"Casey Stoner"}'
./client.raku add 2012 '{"date":"2012-11-11","constructor":"Yamaha","name":"Jorge Lorenzo"}'
./client.raku add 2013 '{"date":"2013-11-10","constructor":"Honda","name":"Marc Márquez"}'
./client.raku add 2014 '{"date":"2014-11-09","constructor":"Honda","name":"Marc Márquez"}'
./client.raku add 2015 '{"date":"2015-11-08","constructor":"Yamaha","name":"Jorge Lorenzo"}'
./client.raku add 2016 '{"date":"2016-11-13","constructor":"Honda","name":"Marc Márquez"}'
./client.raku add 2017 '{"date":"2017-11-12","constructor":"Honda","name":"Marc Márquez"}'
 
./client.raku reportlast
./client.raku reportlastindex constructor
./client.raku reportindex date</pre>
 
=={{header|REBOL}}==
<syntaxhighlight lang="rebol">rebol [author: "Nick Antonaccio"]
write/append %rdb "" db: load %rdb
switch system/options/args/1 [
"new" [write/append %rdb rejoin [now " " mold/only next system/options/args newline]]
"latest" [print copy/part tail sort/skip db 4 -4]
"latestcat" [
foreach cat unique extract at db 3 4 [
t: copy []
foreach [a b c d] db [if c = cat [append t reduce [a b c d]]]
print copy/part tail sort/skip t 4 -4
]
]
"sort" [probe sort/skip db 4]
]
halt</syntaxhighlight>
 
=={{header|REXX}}==
<syntaxhighlight lang="rexx">/* REXX ---------------------------------------------------------------
* 05.10.2014
*--------------------------------------------------------------------*/
x05='05'x
mydb='sidb.txt'
Say 'Enter your commands, ?, or end'
Do Forever
Parse Pull l
Parse Var l command text
Select
When command='?' Then
Call help
When command='add' Then Do
Parse Var text item ',' category ',' date
If date='' Then
date=date('S') /*yyyymmdd*/
Say 'adding item' item'/'category 'dated' date
Call lineout mydb,date item x05 category
End
When command='latest' Then Do
Call lineout mydb
Parse Var text category
hidt='00000000'
ol=''
Do While lines(mydb)>0
l=linein(mydb)
Parse Var l dt a (x05) b
If category=''|,
category='-' & b='' |,
b=category Then Do
If dt>>hidt Then Do
ol=l
hidt=dt
End
End
End
If ol>'' Then
Call o ol
Else
Say 'no matching item found'
End
When command='all' Then Do
Call lineout mydb
Parse Var text category
Do While lines(mydb)>0
l=linein(mydb)
Parse Var l a (x05) b
If category=''|,
category='-' & b=''|,
b=category Then
Call o l
End
End
When command='end' Then
Leave
Otherwise Do
Say 'invalid command ('command')'
Call help
End
End
End
Say 'Bye'
Exit
 
o: Parse Value arg(1) With dt text
Say left(dt,8) text
Return
 
help:
Say 'add item[,[category][,date]] to add an item'
Say 'latest category to list the latest item of a category'
Say 'latest to list the latest item'
Say 'all category to list all items of a category'
Say 'all to list all items'
Say 'end to end this program'
Say 'Use category - to list items without category'
Return</syntaxhighlight>
{{out}}
<pre> Enter your commands, ?, or end
?
add item[,[category][,date]] to add an item
latest category to list the latest item of a category
latest to list the latest item
all category to list all items of a category
all to list all items
end to end this program
Use category - to list items without category
add item1
adding item item1/ dated 20141006
add item2
adding item item2/ dated 20141006
add item3,cat3
adding item item3/cat3 dated 20141006
add item4,cat3,20201910
adding item item4/cat3 dated 20201910
add item5,cat3,190201910
adding item item5/cat3 dated 190201910
all
20141006 item1 �
20141006 item2 �
20141006 item3 � cat3
20201910 item4 � cat3
190201910 item5 � cat3
latest
20201910 item4 � cat3
latest cat1
no matching item found
latest cat3
20201910 item4 � cat3
end
Bye</pre>
 
=={{header|Ruby}}==
<syntaxhighlight lang="ruby">require 'date'
require 'json'
require 'securerandom'
 
class SimpleDatabase
def initialize(dbname, *fields)
@dbname = dbname
@filename = @dbname + ".dat"
@fields = fields
@maxl = @fields.collect {|f| f.length}.max
@data = {
'fields' => fields,
'items' => {},
'history' => [],
'tags' => {},
}
end
attr_reader :dbname, :fields
 
def self.open(dbname)
db = new(dbname)
db.read
db
end
 
def read()
if not File.exists?(@filename)
raise ArgumentError, "Database #@dbname has not been created"
end
@data = JSON.parse(File.read(@filename))
@fields = @data['fields']
@maxl = @fields.collect {|f| f.length}.max
end
 
def write()
File.open(@filename, 'w') {|f| f.write(JSON.generate(@data))}
end
 
def add(*values)
id = SecureRandom.uuid
@data['items'][id] = Hash[ @fields.zip(values) ]
@data['history'] << [Time.now.to_f, id]
id
end
 
def tag(id, *tags)
tags.each do |tag|
if @data['tags'][tag].nil?
@data['tags'][tag] = [id]
else
@data['tags'][tag] << id
end
end
id
end
 
def latest
@data['history'].sort_by {|val| val[0]}.last.last
end
 
def get_item(id)
@data['items'][id]
end
 
def tags()
@data['tags'].keys.sort
end
 
def ids_for_tag(tag)
@data['tags'][tag]
end
 
def tags_for_id(id)
@data['tags'].keys.inject([]) do |tags, tag|
tags << tag if @data['tags'][tag].include?(id)
tags
end
end
 
def display(id)
item = get_item(id)
fmt = "%#{@maxl}s - %s\n"
puts fmt % ['id', id]
@fields.each {|f| print fmt % [f, item[f]]}
puts fmt % ['tags', tags_for_id(id).join(',')]
added = @data['history'].find {|x| x[1] == id}.first
puts fmt % ['date added', Time.at(added).ctime]
puts ""
end
 
def each()
@data['history'].each {|time, id| yield id}
end
 
def each_item_with_tag(tag)
@data['tags'][tag].each {|id| yield id}
end
end
def usage()
puts <<END
usage: #{$0} command args ...
 
commands:
help
create dbname field ...
fields dbname
add dbname value ...
tag dbname id tag ...
tags dbname
list dbname [tag ...]
latest dbname
latest_by_tag dbname
END
end
 
def open_database(args)
dbname = args.shift
begin
SimpleDatabase.open(dbname)
rescue ArgumentError => e
STDERR.puts e.message
exit 1
end
end
 
def process_command_line(command, *args)
case command
when 'help'
usage
 
when 'create'
db = SimpleDatabase.new(*args)
db.write
puts "Database #{args[0]} created"
 
when 'fields'
db = open_database(args)
puts "Database #{db.dbname} fields:"
puts db.fields.join(',')
 
when 'add'
db = open_database(args)
id = db.add(*args)
db.write
puts "Database #{db.dbname} added id #{id}"
 
when 'tag'
db = open_database(args)
id = args.shift
db.tag(id, *args)
db.write
db.display(id)
when 'tags'
db = open_database(args)
puts "Database #{db.dbname} tags:"
puts db.tags.join(',')
 
when 'list'
db = open_database(args)
if args.empty?
db.each {|id| db.display(id)}
else
args.each do |tag|
puts "Items tagged #{tag}"
db.each_item_with_tag(tag) {|id| db.display(id)}
end
end
 
when 'latest'
db = open_database(args)
db.display(db.latest)
 
when 'latest_by_tag'
db = open_database(args)
db.tags.each do |tag|
puts tag
db.display(db.ids_for_tag(tag).last)
end
 
else
puts "Error: unknown command '#{command}'"
usage
end
end
 
process_command_line *ARGV</syntaxhighlight>
 
Sample session
<pre "style='height: 40ex; overflow: scroll">$ ruby simple_database.rb create appointments event_title start_time stop_time location event_description
Database appointments created
$ ruby simple_database.rb add appointments "Wife's Birthday" "2011-11-01" "2011-11-01" "" "happy 39th"
Database appointments added id 6dd02195-1efe-40d1-b43e-c2efd852cd1d
$ ruby simple_database.rb tag appointments 6dd02195-1efe-40d1-b43e-c2efd852cd1d birthday family
id - 6dd02195-1efe-40d1-b43e-c2efd852cd1d
event_title - Wife's Birthday
start_time - 2011-11-01
stop_time - 2011-11-01
location -
event_description - happy 39th
tags - birthday,family
date added - Thu Nov 3 15:52:31 2011
 
$ ruby simple_database.rb add appointments "Parent-Teacher Conference" "2011-11-03 19:30" "2011-11-03 20:00" "school" "desc"
Database appointments added id 0190b835-401d-42da-9ed3-1d335d27b83c
$ ruby simple_database.rb tag appointments 0190b835-401d-42da-9ed3-1d335d27b83c school family
id - 0190b835-401d-42da-9ed3-1d335d27b83c
event_title - Parent-Teacher Conference
start_time - 2011-11-03 19:30
stop_time - 2011-11-03 20:00
location - school
event_description - desc
tags - family,school
date added - Thu Nov 3 15:54:05 2011
 
$ ruby simple_database.rb add appointments "Buy gift for wife" "2011-10-31 16:00" "2011-10-31 16:30" "the mall" "hmm, maybe jewelery?"
Database appointments added id 4023e6f1-bcc1-49e5-a59f-138157b413f4
$ ruby simple_database.rb tag appointments 4023e6f1-bcc1-49e5-a59f-138157b413f4 family last-minute
id - 4023e6f1-bcc1-49e5-a59f-138157b413f4
event_title - Buy gift for wife
start_time - 2011-10-31 16:00
stop_time - 2011-10-31 16:30
location - the mall
event_description - hmm, maybe jewelery?
tags - family,last-minute
date added - Thu Nov 3 15:55:02 2011
 
$ ruby simple_database.rb fields appointments
Database appointments fields:
event_title,start_time,stop_time,location,event_description
$ ruby simple_database.rb tags appointments
Database appointments tags:
birthday,family,last-minute,school
$ ruby simple_database.rb list appointments
id - 6dd02195-1efe-40d1-b43e-c2efd852cd1d
event_title - Wife's Birthday
start_time - 2011-11-01
stop_time - 2011-11-01
location -
event_description - happy 39th
tags - birthday,family
date added - Thu Nov 3 15:52:31 2011
 
id - 0190b835-401d-42da-9ed3-1d335d27b83c
event_title - Parent-Teacher Conference
start_time - 2011-11-03 19:30
stop_time - 2011-11-03 20:00
location - school
event_description - desc
tags - family,school
date added - Thu Nov 3 15:54:05 2011
 
id - 4023e6f1-bcc1-49e5-a59f-138157b413f4
event_title - Buy gift for wife
start_time - 2011-10-31 16:00
stop_time - 2011-10-31 16:30
location - the mall
event_description - hmm, maybe jewelery?
tags - family,last-minute
date added - Thu Nov 3 15:55:02 2011
$ cat appointments.dat
{"fields":["event_title","start_time","stop_time","location","event_description"],"items":{"6dd02195-1efe-40d1-b43e-c2efd852cd1d":{"event_title":"Wife's Birthday","start_time":"2011-11-01","stop_time":"2011-11-01","location":"","event_description":"happy 39th"},"0190b835-401d-42da-9ed3-1d335d27b83c":{"event_title":"Parent-Teacher Conference","start_time":"2011-11-03 19:30","stop_time":"2011-11-03 20:00","location":"school","event_description":"desc"},"4023e6f1-bcc1-49e5-a59f-138157b413f4":{"event_title":"Buy gift for wife","start_time":"2011-10-31 16:00","stop_time":"2011-10-31 16:30","location":"the mall","event_description":"hmm, maybe jewelery?"}},"history":[[1320349951.000625,"6dd02195-1efe-40d1-b43e-c2efd852cd1d"],[1320350045.4736252,"0190b835-401d-42da-9ed3-1d335d27b83c"],[1320350102.9486248,"4023e6f1-bcc1-49e5-a59f-138157b413f4"]],"tags":{"birthday":["6dd02195-1efe-40d1-b43e-c2efd852cd1d"],"family":["6dd02195-1efe-40d1-b43e-c2efd852cd1d","0190b835-401d-42da-9ed3-1d335d27b83c","4023e6f1-bcc1-49e5-a59f-138157b413f4"],"school":["0190b835-401d-42da-9ed3-1d335d27b83c"],"last-minute":["4023e6f1-bcc1-49e5-a59f-138157b413f4"]}}
</pre>
 
=={{header|Scala}}==
<syntaxhighlight lang="scala">object SimpleDatabase extends App {
type Entry = Array[String]
def asTSV(e: Entry) = e mkString "\t"
def fromTSV(s: String) = s split "\t"
val header = asTSV(Array("TIMESTAMP", "DESCRIPTION", "CATEGORY", "OTHER"))
 
def read(filename: String) = try {
scala.io.Source.fromFile(filename).getLines.drop(1).map(fromTSV)
} catch {
case e: java.io.FileNotFoundException => Nil
}
 
def write(filename: String, all: Seq[Entry]) = {
import java.nio.file.{Files,Paths}
import scala.collection.JavaConversions.asJavaIterable
Files.write(Paths.get(filename), asJavaIterable(header +: all.map(asTSV)))
all.size
}
 
def add(filename: String, description: String, category: String = "none", optional: Seq[String] = Nil) {
val format = new java.text.SimpleDateFormat("yyyy-MM-dd HH:mm:ss")
val e = Array(format.format(new java.util.Date), description, category) ++ optional
println(write(filename, read(filename).toBuffer :+ e) + " entries")
}
 
def print(filename: String, filter: Seq[Entry] => TraversableOnce[Entry]) =
filter(read(filename).toList.sortBy(_.headOption)) map(_ mkString ",") foreach println
 
args match {
case Array(f, "latest") => print(f, _ takeRight 1)
case Array(f, "latest", cat) => print(f, _ filter(_.lift(2) == Some(cat)) takeRight 1)
case Array(f, "all") => print(f, _.toSeq)
case Array(f, "all", "latest") => print(f, _ groupBy (_ lift 2 getOrElse "") map{case (_, cat) => cat.last})
case Array(f, "add", desc) => add(f, desc, category = "")
case Array(f, "add", desc, cat, opt @ _*) => add(f, desc, cat, opt)
case _ => println("Usage: SimpleDatabase filename.tsv [all [latest]| latest [CATEGORY] | add [DESCRIPTION [CATEGORY [OPTIONAL]...]]]")
}
}</syntaxhighlight>
{{out}}
<pre>> SimpleDatabase
Usage: SimpleDatabase filename.tsv [all [latest]| latest [CATEGORY] | add [DESCRIPTION [CATEGORY [OPTIONAL]...]]]
 
> SimpleDatabase database.tsv all
 
> SimpleDatabase database.tsv add one
1 entries
 
> SimpleDatabase database.tsv add two test
2 entries
 
> SimpleDatabase database.tsv add three test optional
3 entries
 
> SimpleDatabase database.tsv add four final
4 entries
 
> SimpleDatabase database.tsv all
2014-10-03 12:00:01,one
2014-10-03 12:00:02,two,test
2014-10-03 12:00:03,three,test,optional
2014-10-03 12:00:04,four,final
 
> SimpleDatabase database.tsv all latest
2014-10-03 12:00:04,four,final
2014-10-03 12:00:03,three,test,optional
2014-10-03 12:00:01,one
 
> SimpleDatabase database.tsv latest
2014-10-03 12:00:04,four,final
 
> SimpleDatabase database.tsv latest test
2014-10-03 12:00:03,three,test,optional</pre>
 
=={{header|Tcl}}==
The format used is that of a Tcl dictionary, where each entry uses the title as a key and the remaining information (category, date and miscellaneous metadata) is the value associated with it. The only variation from the standard internal format is that entries are separated by newlines instead of spaces; this is still a legal value, but is a non-canonical.
<syntaxhighlight lang="tcl">#!/usr/bin/env tclsh8.6
package require Tcl 8.6
namespace eval udb {
variable db {}
 
proc Load {filename} {
variable db
if {[catch {set f [open $filename]}]} {
set db {}
return
}
set db [read $f]
close $f
}
proc Store {filename} {
variable db
if {[catch {set f [open $filename w]}]} return
dict for {nm inf} $db {
puts $f [list $nm $inf]
}
close $f
}
 
proc add {title category {date "now"} args} {
variable db
if {$date eq "now"} {
set date [clock seconds]
} else {
set date [clock scan $date]
}
dict set db $title [list $category $date $args]
return
}
proc Rec {nm cat date xtra} {
dict create description $nm category $cat date [clock format $date] \
{*}$xtra _names [dict keys $xtra]
}
proc latest {{category ""}} {
variable db
if {$category eq ""} {
set d [lsort -stride 2 -index {1 1} -integer -decreasing $db]
dict for {nm inf} $d break
return [list [Rec $nm {*}$inf]]
}
set latestbycat {}
dict for {nm inf} [lsort -stride 2 -index {1 1} -integer $db] {
dict set latestbycat [lindex $inf 0] [list $nm {*}$inf]
}
return [list [Rec {*}[dict get $latestbycat $category]]]
}
proc latestpercategory {} {
variable db
set latestbycat {}
dict for {nm inf} [lsort -stride 2 -index {1 1} -integer $db] {
dict set latestbycat [lindex $inf 0] [list $nm {*}$inf]
}
set result {}
dict for {- inf} $latestbycat {
lappend result [Rec {*}$inf]
}
return $result
}
proc bydate {} {
variable db
set result {}
dict for {nm inf} [lsort -stride 2 -index {1 1} -integer $db] {
lappend result [Rec $nm {*}$inf]
}
return $result
}
 
namespace export add latest latestpercategory bydate
namespace ensemble create
}
 
if {$argc < 2} {
puts stderr "wrong # args: should be \"$argv0 dbfile subcommand ?args...?\""
exit 1
}
udb::Load [lindex $argv 0]
set separator ""
if {[catch {udb {*}[lrange $argv 1 end]} msg]} {
puts stderr [regsub "\"udb " $msg "\"$argv0 dbfile "]
exit 1
}
foreach row $msg {
puts -nonewline $separator
apply {row {
dict with row {
puts "Title: $description"
puts "Category: $category"
puts "Date: $date"
foreach v $_names {
puts "${v}: [dict get $row $v]"
}
}
}} $row
set separator [string repeat - 70]\n
}
 
udb::Store [lindex $argv 0]</syntaxhighlight>
Sample session:
<syntaxhighlight lang="bash">bash$ udb.tcl db
wrong # args: should be "udb.tcl dbfile subcommand ?args...?"
bash$ udb.tcl db ?
unknown or ambiguous subcommand "?": must be add, bydate, latest, or latestpercategory
bash$ udb.tcl db add
wrong # args: should be "udb.tcl dbfile add title category ?date? ?arg ...?"
bash$ udb.tcl db add "Title 1" foo
bash$ udb.tcl db add "Title 2" foo
bash$ udb.tcl db add "Title 3" bar
bash$ udb.tcl db bydate
Title: Title 1
Category: foo
Date: Tue Nov 15 18:11:58 GMT 2011
----------------------------------------------------------------------
Title: Title 2
Category: foo
Date: Tue Nov 15 18:12:01 GMT 2011
----------------------------------------------------------------------
Title: Title 3
Category: bar
Date: Tue Nov 15 18:12:07 GMT 2011
bash$ udb.tcl db latest
Title: Title 3
Category: bar
Date: Tue Nov 15 18:12:07 GMT 2011
bash$ udb.tcl db latest foo
Title: Title 2
Category: foo
Date: Tue Nov 15 18:12:01 GMT 2011
bash$ udb.tcl db latest bar
Title: Title 3
Category: bar
Date: Tue Nov 15 18:12:07 GMT 2011
bash$ udb.tcl db latestpercategory
Title: Title 2
Category: foo
Date: Tue Nov 15 18:12:01 GMT 2011
----------------------------------------------------------------------
Title: Title 3
Category: bar
Date: Tue Nov 15 18:12:07 GMT 2011
bash$ udb.tcl db add "Title 4" bar "12:00 Monday last week"
bash$ udb.tcl db bydate
Title: Title 4
Category: bar
Date: Mon Nov 14 12:00:00 GMT 2011
----------------------------------------------------------------------
Title: Title 1
Category: foo
Date: Tue Nov 15 18:11:58 GMT 2011
----------------------------------------------------------------------
Title: Title 2
Category: foo
Date: Tue Nov 15 18:12:01 GMT 2011
----------------------------------------------------------------------
Title: Title 3
Category: bar
Date: Tue Nov 15 18:12:07 GMT 2011
bash$ cat db
{Title 1} {foo 1321380718 {}}
{Title 2} {foo 1321380721 {}}
{Title 3} {bar 1321380727 {}}
{Title 4} {bar 1321272000 {}}
bash$ udb.tcl db add "Title 5" foo "12:00 Monday last week" Comment 'Wholly excellent!'
bash$ cat db
{Title 1} {foo 1321380718 {}}
{Title 2} {foo 1321380721 {}}
{Title 3} {bar 1321380727 {}}
{Title 4} {bar 1321272000 {}}
{Title 5} {foo 1321272000 {Comment {Wholly excellent!}}}
bash$ udb.tcl db bydate
Title: Title 4
Category: bar
Date: Mon Nov 14 12:00:00 GMT 2011
----------------------------------------------------------------------
Title: Title 5
Category: foo
Date: Mon Nov 14 12:00:00 GMT 2011
Comment: Wholly excellent!
----------------------------------------------------------------------
Title: Title 1
Category: foo
Date: Tue Nov 15 18:11:58 GMT 2011
----------------------------------------------------------------------
Title: Title 2
Category: foo
Date: Tue Nov 15 18:12:01 GMT 2011
----------------------------------------------------------------------
Title: Title 3
Category: bar
Date: Tue Nov 15 18:12:07 GMT 2011</syntaxhighlight>
 
=={{header|ToffeeScript}}==
<syntaxhighlight lang="coffeescript">#!/usr/local/bin/toffee
 
prog = require 'commander'
fs = require 'fs-extra'
 
if not fs.exists! 'data.json'
fs.outputJson! 'data.json', {}
 
prog
.command('add <name> <category> [date]')
.description('Add a new entry')
.option('-n <text>', 'notes')
.option('-t <tags>', 'tags')
.action addentry
 
prog
.command('latest')
.description('Print the latest entry')
.action latest
 
prog
.command('catlatest')
.description('Print the latest entry for each category')
.action catlatestout
 
prog
.command('list')
.description('Print all entries sorted by date')
.action bydate
 
 
addentry = (name, category, dt, options) ->
if dt? then dat = new Date(dt) else dat = new Date()
update =
name: name
category: category
tags: options?.T
notes: options?.N
date: dat.getTime()
e, data = fs.readJson! 'data.json'
if not data[category]?
data[category] = []
data[category].push update
fs.outputJson 'data.json', data
 
byDateNew = (a, b) ->
if a.date<b.date then return 1
if b.date>a.date then return -1
return 0
 
catlatest = (cb) ->
e, data = fs.readJson! 'data.json'
ret = []
for cat, list of data
list.sort byDateNew
ret.push list[0]
cb ret
 
printFormatted = (entry) ->
tmp = entry.date
entry.date = new Date(entry.date).toDateString()
console.log entry
entry.date = tmp
 
latest = ->
newpercat = catlatest!
newpercat.sort byDateNew
printFormatted newpercat[0]
 
catlatestout = ->
items = catlatest!
for item in items
printFormatted item
 
bydate = ->
e, data = fs.readJson! 'data.json'
entries = []
for cat, list of data
for item in list
entries.push item
entries.sort byDateNew
for entry in entries
printFormatted entry
 
prog.parse process.argv</syntaxhighlight>
The fileformat on disk should be human readable, but it need not be standardized. A natively available format that doesn't need an external library is preferred. Avoid developing your own format however if you can use an already existing one. If there is no existing format available pick one of: [[JSON]], [[S-Expressions]], YAML, or [[wp:Comparison_of_data_serialization_formats|others]].
 
=={{header|UnixUNIX Shell}}==
This format is guaranteed to be human readable: if you can type it, you can read it.
<langsyntaxhighlight lang="bash">#!/bin/sh
 
db_create() {
Line 120 ⟶ 5,264:
show_help
;;
esac</langsyntaxhighlight>
Sample usage (assuming script is named "sdb"):<syntaxhighlight lang="text">$ sdb create CDs
Create DB `CDs'
$ sdb create CDs
Create DB `CDs'
$ sdb add CDs Bookends
Line 159 ⟶ 5,301:
$ sdb drop CDs
Delete DB `CDs'
$</langsyntaxhighlight>
 
=={{header|Wren}}==
{{trans|Kotlin}}
===Version 1===
{{libheader|Wren-ioutil}}
{{libheader|Wren-trait}}
{{libheader|Wren-iterate}}
{{libheader|Wren-date}}
{{libheader|Wren-sort}}
{{libheader|Wren-str}}
Note that since Wren CLI currently has no way of determining the current date/time, a date needs to be input for each item to be added.
<syntaxhighlight lang="wren">/* Simple_database.wren */
 
import "os" for Process
import "./ioutil" for File, FileFlags, FileUtil
import "./trait" for Comparable
import "./iterate" for Reversed
import "./date" for Date
import "./sort" for Sort
import "./str" for Str
 
var fileName = "Simple_database.csv"
 
Date.default = Date.isoDate
 
class Item is Comparable {
construct new(name, date, category) {
_name = name
_date = date
_category = category
}
 
name { _name }
date { _date }
category { _category }
 
compare(other) { _date.compare(other.date) }
 
toString { "%(name), %(date.toString), %(category)" }
}
 
var printUsage = Fn.new {
System.print("""
Usage:
wren Simple_database.wren cmd [categoryName]
add add item name and date, followed by optional category
latest print item with latest date, followed by optional category
all print all
For instance: add "some item name", "some item date", "some category name"
Dates should be in format: yyyy-mm-dd
""")
}
 
var load = Fn.new {
var db = []
var lines = FileUtil.readLines(fileName)
for (line in lines) {
if (line == "") break // end of file
var item = line.split(", ")
db.add(Item.new(item[0], Date.parse(item[1]), item[2]))
}
return db
}
 
var store = Fn.new { |item|
File.openWithFlags(fileName, FileFlags.writeOnly) { |f|
f.writeBytes("%(item)\n")
}
}
 
var addItem = Fn.new { |input|
if (input.count < 2) {
printUsage.call()
return
}
var date = Date.parse(input[1])
var cat = (input.count == 3) ? input[2] : "none"
store.call(Item.new(input[0], date, cat))
}
 
var printLatest = Fn.new { |a|
var db = load.call()
if (db.isEmpty) {
System.print("No entries in database.")
return
}
Sort.quick(db) // sort by ascending date
if (a.count == 1) {
var found = false
for (item in Reversed.new(db)) {
if (item.category == a[0]) {
System.print(item)
found = true
break
}
}
if (!found) System.print("There are no items for category '%(a[0])'.")
} else System.print(db[-1])
}
 
var printAll = Fn.new {
var db = load.call()
if (db.isEmpty) {
System.print("No entries in database.")
return
}
Sort.quick(db) // sort by ascending date
for (item in db) System.print(item)
}
 
var args = Process.arguments
if (!(1..4).contains(args.count)) {
printUsage.call()
return
}
// create file if it doesn't already exist
if (!File.exists(fileName)) {
var f = File.create(fileName)
f.close()
}
 
var cmd = Str.lower(args[0])
if (cmd == "add") {
addItem.call(args[1..-1])
} else if (cmd == "latest") {
printLatest.call(args[1..-1])
} else if (cmd == "all") {
printAll.call()
} else {
printUsage.call()
}</syntaxhighlight>
 
{{out}}
Sample session:
<pre>
$ wren Simple_database.wren add item1 2021-03-01
$ wren Simple_database.wren add item2 2021-04-01
$ wren Simple_database.wren add item3 2021-05-01 cat3
$ wren Simple_database.wren add item4 2021-06-01 cat3
$ wren Simple_database.wren add item5 2021-07-01 cat3
$ wren Simple_database.wren latest
item5, 2021-07-01, cat3
$ wren Simple_database.wren latest none
item2, 2021-04-01, none
$ wren Simple_database.wren latest cat4
There are no items for category 'cat4'.
$ wren Simple_database.wren all
item1, 2021-03-01, none
item2, 2021-04-01, none
item3, 2021-05-01, cat3
item4, 2021-06-01, cat3
item5, 2021-07-01, cat3
</pre>
<br>
===Version 2===
{{libheader|Wren-table}}
The above module provides a more generic way to create simple databases and was not available when the first version was written.
<syntaxhighlight lang="wren">import "os" for Process
import "./table" for Table, FieldInfo, File
import "./str" for Str
 
var printUsage = Fn.new {
System.print("""
Usage:
wren Simple_database.wren cmd [categoryName]
add add item name and date, followed by optional category
latest print item with latest date, followed by optional category
all print all
For instance: add "some item name", "some item date", "some category name"
Dates should be in format: yyyy-mm-dd
""")
}
 
var printLatest = Fn.new { |table, a|
if (table.isEmpty) {
System.print("No entries in table.")
return
}
var records = table.records
records.sort { |s, t| Str.lt(s[1], t[1]) } // sort by ascending date
if (a.count == 1) {
var found = false
for (record in records[-1..0]) {
if (record[2] == a[0]) {
System.print(record)
found = true
break
}
}
if (!found) System.print("There are no records for category '%(a[0])'.")
} else System.print(records[-1])
}
 
var args = Process.arguments
if (!(1..4).contains(args.count)) {
printUsage.call()
return
}
 
// create a new Table object
var tableName = "Simple_database"
var table
if (Table.fileExists(tableName)) {
table = Table.load(tableName)
} else {
var fis = [
FieldInfo.new("name", String),
FieldInfo.new("date", String),
FieldInfo.new("category", String)
]
table = Table.new(tableName, fis)
}
 
var cmd = Str.lower(args[0])
if (cmd == "add") {
if (args.count < 4) args.add("none")
table.add(args[1..-1])
table.save()
} else if (cmd == "latest") {
printLatest.call(table, args[1..-1])
} else if (cmd == "all") {
table.list()
} else {
printUsage.call()
}</syntaxhighlight>
 
{{out}}
<pre>
$ wren Simple_database.wren add item1 2021-03-01
$ wren Simple_database.wren add item2 2021-04-01
$ wren Simple_database.wren add item3 2021-05-01 cat3
$ wren Simple_database.wren add item4 2021-06-01 cat3
$ wren Simple_database.wren add item5 2021-07-01 cat3
$ wren Simple_database.wren latest
[item5, 2021-07-01, cat3]
$ wren Simple_database.wren latest none
[item2, 2021-04-01, none]
$ wren Simple_database.wren latest cat4
There are no records for category 'cat4'.
$ wren Simple_database.wren all
Records in 'Simple_database' table:
 
name date category
----- ---------- --------
item1 2021-03-01 none
item2 2021-04-01 none
item3 2021-05-01 cat3
item4 2021-06-01 cat3
item5 2021-07-01 cat3
</pre>
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