Simple database

Simple database is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

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 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 CD collection, your friends birthdays, or diary.

You should track the following details:

• A description of the item. (eg title, name)
• A category or tag (genre, topic, relationship (friend, 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

The command should support the following Command-line arguments to run:

• Add a new entry
• Print the latest entry
• Print the latest entry for each category
• Print all entries sorted by a date

The category may be realized as a tag or as structure (making all entries in that category subitems)

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 others.

Unix Shell

This format is guaranteed to be human readable: if you can type it, you can read it. <lang bash>#!/bin/sh

db_create() { mkdir ./"$1" && mkdir "./$1/.tag" && echo "Create DB \`$1'" }

db_delete() { rm -r ./"$1" && echo "Delete DB \`$1'" }

db_show() { if [ -z "$2" ]; then show_help; fi for x in "./$1/$2/"*; do echo "$x:" | sed "s/.*\///" cat "$x" | sed "s/^/ /" echo done

printf "Tags: " ls "./$1/$2/.tag" }

db_tag() { local db="$1" item="$2" shift shift for tag in $@; do mkdir "./$db/.tag/$tag" ln -s "$PWD/$db/$item" "./$db/.tag/$tag/" touch "./$db/$item/.tag/$tag" done }

show_help() { echo "Usage: $0 command [args]" echo "Commands:" cat $0 | grep ") ##" | grep -v grep | sed 's/) ## /:\t/' exit }

if [ -z "$1" ]; then show_help; fi

action=$1 it=database shift case $action in create) ## db -- create $it db_create "$@" ;;

drop) ## db -- delete $it db_delete "$@" ;;

add) ## db item -- add new item to $it mkdir -p "./$1/$2/.tag" && touch "./$1/$2/Description" ;;

rem) ## db item -- delete item from $it rm -r "./$1/$2" rm "./$1/.tag/"*"/$2" ;;

show) ## db item -- show item db_show "$@" ;;

newtag) ## db new-tag-name -- create new tag name mkdir "./$1/.tag/$2" ;;

prop) ## db item property-name property-content -- add property to item echo "$4" > "./$1/$2/$3" ;;

tag) ## db item tag [more-tags...] -- mark item with tags db_tag "$@" ;;

last) ## db -- show latest item ls "$1" --sort=time | tail -n 1 ;;

list) ## db -- list all items ls "$1" -1 --sort=time ;;

last-all) ## db -- list items in each category for x in "$1/.tag/"*; do echo "$x" | sed 's/.*\//Tag: /' printf " " ls "$x" --sort=time | tail -n 1 echo done ;;

help) ## this message show_help ;;

*) echo Bad DB command: $1 show_help ;; esac</lang> Sample usage (assuming script is named "sdb"):<lang>$ sdb create CDs Create DB `CDs' $ sdb create CDs Create DB `CDs' $ sdb add CDs Bookends $ sdb prop CDs Bookends artists "Simon & Garfunkel" $ sdb add CDs "Ode to joy" $ sdb prop CDs "Ode to joy" artist "Beethoven" $ sdb tag CDs Bookends rock folk # I'm not sure about this $ sdb tag CDs "Ode to joy" classical $ sdb show CDs Bookends Description:

artists:

   Simon & Garfunkel

Tags: folk rock $ sdb prop CDs "Ode to joy" Description "Sym. No. 9" $ sdb show CDs "Ode to joy" Description:

   Sym. No. 9

artist:

   Beethoven

Tags: classical $ sdb last-all CDs Tag: classical

   Ode to joy

Tag: folk

   Bookends

Tag: rock

   Bookends

$ sdb drop CDs Delete DB `CDs' $</lang>