COALESCE

Syntax

 COALESCE (expression_list)

Description

Returns the first non-NULL expression from a list. At least two expressions must be contained in expression_list, and all expressions must be comparable. The result will be NULL if all the arguments are NULL.

Example

 CREATE TABLE coalesce_example (ID INT PRIMARY KEY, A REAL, B REAL);
 INSERT INTO coalesce_example VALUES(1, 100, 80);
 INSERT INTO coalesce_example VALUES(2, NULL, 63);
 INSERT INTO coalesce_example VALUES(3, NULL, NULL);

 SELECT id, a, b, COALESCE (a, b*1.1, 50.0) "coalesce" FROM coalesce_example;

ID	A	B	coalesce
1	100.0	80.0	100.0
2	NULL	63.0	69.30000305175781
3	NULL	NULL	50.0