podoc:concat_ignore_null_sql_function
Database Function Description of "concat_ignore_null"
Name
concat_ignore_null
Description
This function will concatenate two strings.
The concatenation operator || has been redefined to use this function.
Purpose
This function will concatenate two strings. The difference from the || operator is that our function will ignore null arguments.
Schema
CREATE FUNCTION concat_ignore_null(VARCHAR, VARCHAR) RETURNS VARCHAR AS ' declare string_1 alias for $1; string_2 alias for $2; begin if string_1 is null then return string_2; end if; if string_2 is null then return string_1; end if; return string_1||string_2; end; ' LANGUAGE 'plpgsql' ; -- concat operator that ignores null arguments CREATE operator ||| ( leftarg = VARCHAR, rightarg = VARCHAR, PROCEDURE = concat_ignore_null );
History
Used first
Version 2.16
Used last
Still in use
Change history
= Version 2.16 =
-- this function will concatenate two strings -- the difference from the || operator is that our function -- will ignore null arguments CREATE FUNCTION concat_ignore_null(VARCHAR, VARCHAR) RETURNS VARCHAR AS ' declare string_1 alias for $1; string_2 alias for $2; begin if string_1 is null then return string_2; end if; if string_2 is null then return string_1; end if; return string_1||string_2; end; ' LANGUAGE 'plpgsql' ; -- concat operator that ignores null arguments CREATE operator ||| ( leftarg = VARCHAR, rightarg = VARCHAR, PROCEDURE = concat_ignore_null );
podoc/concat_ignore_null_sql_function.txt · Last modified: 2007/04/23 14:25 by Luud