Доки для кого пишут?
* New COALESCE internal function (SF #451917).
Allow a column value to be calculated by a number of expressions, the first expression returning a non NULL value is returned as the column value.
Syntax:
COALESCE (value {, value} ... )
Notes:
1. COALESCE (V1, V2) is equivalent to the following case specification:
CASE WHEN V1 IS NOT NULL THEN V1 ELSE V2 END
2. COALESCE (V1, V2, ..., Vn), for n >= 3, is equivalent to the following case specification:
CASE WHEN V1 IS NOT NULL THEN V1 ELSE COALESCE (V2, ..., Vn) END
3. The function has the same meaning as NVL one in Oracle.
Example:
SELECT
PROJ_NAME AS Projectname,
COALESCE(e.FULL_NAME, '[> not assigned <]') AS Employeename
FROM
PROJECT p LEFT JOIN EMPLOYEE e ON (e.EMP_NO = p.TEAM_LEADER)
Contributor(s):
Arno Brinkman <firebird@abvisie.nl>;