COALESCE
语法:
COALESCE(value,...)
说明:
返回结果中第一个非空的值，如果结果集中都不为空，则返回null。最后一个参数必须赋值。
例子:
MariaDB [(none)]> SELECT COALESCE(NULL,1); +------------------+ | COALESCE(NULL,1) | +------------------+ | 1 | +------------------+ 1 row in set (0.00 sec) MariaDB [(none)]> SELECT COALESCE(NULL,NULL,NULL); +--------------------------+ | COALESCE(NULL,NULL,NULL) | +--------------------------+ | NULL | +--------------------------+ 1 row in set (0.00 sec) MariaDB [(none)]>
Content reproduced on this site is the property of its respective owners,
and this content is not reviewed in advance by MariaDB. The views, information and opinions
expressed by this content do not necessarily represent those of MariaDB or any other party.
