coalesce
description
Syntax
coalesce(expr1, expr2, ...., expr_n))
返回参数中的第一个非空表达式（从左向右）
example
mysql> select coalesce(NULL, '1111', '0000');
+--------------------------------+
| coalesce(NULL, '1111', '0000') |
+--------------------------------+
| 1111 |
+--------------------------------+keywords
COALESCE