mirror of
https://github.com/FirebirdSQL/firebird.git
synced 2025-01-22 20:43:02 +01:00
42 lines
1.1 KiB
Plaintext
42 lines
1.1 KiB
Plaintext
|
SQL Language Extension: LIST
|
||
|
|
|
||
|
|
Function:
|
||
|
|
This function returns a string result with the concatenated non-NULL
|
||
|
|
values from a group. It returns NULL if there are no non-NULL values.
|
||
|
|
|
||
|
|
Authors:
|
||
|
|
Oleg Loa <loa@mail.ru>
|
||
|
|
Dmitry Yemanov <dimitr@firebird.org>
|
||
|
|
|
||
|
|
Format:
|
||
|
|
|
||
|
|
<list function> ::=
|
||
|
|
LIST '(' [ {ALL | DISTINCT} ] <value expression> [',' <delimiter value> ] ')'
|
||
|
|
|
||
|
|
<delimiter value> ::=
|
||
|
|
{ <string literal> | <parameter> | <variable> }
|
||
|
|
|
||
|
|
Syntax Rules:
|
||
|
|
1) If neither ALL nor DISTINCT is specified, ALL is implied.
|
||
|
|
2) If <delimiter value> is omitted, a comma is used to separate
|
||
|
|
the concatenated values.
|
||
|
|
|
||
|
|
Notes:
|
||
|
|
1) Numeric and datetime values are implicitly converted to strings
|
||
|
|
during evaluation.
|
||
|
|
2) The result value is of type VARCHAR(32765), so the LIST function
|
||
|
|
should be used carefully, as Firebird limits the maximum
|
||
|
|
result set width by 64KB.
|
||
|
|
3) Ordering of values within a group is implementation-defined.
|
||
|
|
|
||
|
|
Examples:
|
||
|
|
|
||
|
|
A)
|
||
|
|
SELECT LIST(ID, ':')
|
||
|
|
FROM MY_TABLE
|
||
|
|
|
||
|
|
B)
|
||
|
|
SELECT TAG_TYPE, LIST(TAG_VALUE)
|
||
|
|
FROM TAGS
|
||
|
|
GROUP BY TAG_TYPE
|