coalesce
description
Syntax
coalesce(expr1, expr2, ...., expr_n)
Returns the first non empty expression in the parameter (from left to right)
example
mysql> select coalesce(NULL, '1111', '0000');
+--------------------------------+
| coalesce(NULL, '1111', '0000') |
+--------------------------------+
| 1111 |
+--------------------------------+keywords
COALESCE