contact用法解析
经典用法:
mysql> select concat('11','22','33'); +------------------------+ | concat('11','22','33') | +------------------------+ | 112233 | +------------------------+ 1 row in set (0.00 sec) MySQL的concat函数在连接字符串的时候,只要其中一个是NULL,那么将返回NULL mysql> select concat('11','22',null); +------------------------+ | concat('11','22',null) | +------------------------+ | NULL | +------------------------+ 1 row in set (0.00 sec)
实战演练:
SELECT eg.* FROM wanghaokuneg eg WHERE CONCAT(eg.c,eg.e,eg.b) IN (6103) 表数据: a b c d e f g 2 3 61 涤纶 0 0 0