Table creation: Difference between revisions
→{{header|Wren}}: Added a second version based on the new Wren-table module.
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=={{header|Wren}}==
===Version 1===
{{libheader|Wren-dynamic}}
{{libheader|Wren-fmt}}
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In practice, a binary search would be needed to find records quickly by key given that the records are being maintained in sorted order. However, for now we use a sequential search instead.
<syntaxhighlight lang="ecmascript">import "./dynamic" for Enum, Tuple
import "./fmt" for Fmt
import "./sort" for Cmp, Sort
var FieldType = Enum.create("FieldType", ["text", "num", "int", "bool"])
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2 2006-03-28 BUY IBM 1000 45.00 true
4 2006-04-05 BUY MSOFT 1000 72.00 false
</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="ecmascript">import "./table" for FieldInfo, Table, Records
var fields = [
FieldInfo.new("id", Num),
FieldInfo.new("date", String),
FieldInfo.new("trans", String),
FieldInfo.new("sym", String),
FieldInfo.new("qty", Num),
FieldInfo.new("price", Num),
FieldInfo.new("settled", Bool)
]
// create table
var table = Table.new("Stock_transactions", fields)
// add records
table.add([3, "2006-04-06", "SELL", "IBM" , 500, 53.00, true ])
table.add([1, "2006-01-05", "BUY" , "RHAT" , 100, 35.14, true ])
table.add([4, "2006-04-05", "BUY" , "MSOFT", 1000, 72.00, false])
table.add([2, "2006-03-28", "BUY" , "IBM" , 1000, 45.00, true ])
var colWidths = [2, 10, 4, 5, 4, 5.2, 7] // for listings
// show the table's fields
table.listFields()
System.print()
// sort the records by 'id' and show them
var sortFn = Fn.new { |s, t| s[0] < t[0] }
var records = table.sortedRecords(sortFn)
Records.list(table.fields, records, "Records for %(table.name) table:\n", colWidths)
// find a record by key
System.print("\nThe record with an id of 2 is:")
System.print(table.find(2))
// delete a record by key
table.remove(3)
System.print("\nThe record with an id of 3 will be deleted, leaving:\n")
records = table.sortedRecords(sortFn)
Records.list(table.fields, records, "Records for %(table.name) table:\n", colWidths)</syntaxhighlight>
{{out}}
<pre>
Fields for Stock_transactions table:
name kind
------- ------
id Num
date String
trans String
sym String
qty Num
price Num
settled Bool
Records for Stock_transactions table:
id date tran sym qty price settled
-- ---------- ---- ----- ---- ----- -------
1 2006-01-05 BUY RHAT 100 35.14 true
2 2006-03-28 BUY IBM 1000 45.00 true
3 2006-04-06 SELL IBM 500 53.00 true
4 2006-04-05 BUY MSOFT 1000 72.00 false
The record with an id of 2 is:
[2, 2006-03-28, BUY, IBM, 1000, 45, true]
The record with an id of 3 will be deleted, leaving:
Records for Stock_transactions table:
id date tran sym qty price settled
-- ---------- ---- ----- ---- ----- -------
1 2006-01-05 BUY RHAT 100 35.14 true
2 2006-03-28 BUY IBM 1000 45.00 true
4 2006-04-05 BUY MSOFT 1000 72.00 false
</pre>
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