Function: 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 Author: Arno Brinkman Format: ::= | COALESCE { }... Syntax Rules: 1) COALESCE (V1, V2) is equivalent to the following : 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 WHEN V1 IS NOT NULL THEN V1 ELSE COALESCE (V2,...,Vn) END Examples: A) 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) B) SELECT COALESCE(Phone,MobilePhone,'Unknown') AS "Phonenumber" FROM Relations