MySQL通配符过滤数据

LIKE操作符

百分号（%）通配符

mysql> select * from user where name like '%3';+----+-------+| id | name  |+----+-------+|  3 | user3 |+----+-------+1 row in set (0.00 sec)

mysql> select * from user where name like 'user%';+----+-------+| id | name  |+----+-------+|  1 | user1 ||  2 | user2 ||  3 | user3 ||  4 | user4 ||  5 | user5 |+----+-------+5 rows in set (0.00 sec)

mysql> select * from user where name like '%er%';+----+-------+| id | name  |+----+-------+|  1 | user1 ||  2 | user2 ||  3 | user3 ||  4 | user4 ||  5 | user5 |+----+-------+5 rows in set (0.00 sec)//不能用'%'来代替NULL。

下划线（_）通配符

mysql> select * from user where name like 'user_';+----+-------+| id | name  |+----+-------+|  1 | user1 ||  2 | user2 ||  3 | user3 ||  4 | user4 ||  5 | user5 |+----+-------+5 rows in set (0.00 sec)

mysql> select * from user where name like '_ser_';+----+-------+| id | name  |+----+-------+|  1 | user1 ||  2 | user2 ||  3 | user3 ||  4 | user4 ||  5 | user5 |+----+-------+5 rows in set (0.00 sec)

mysql> select * from content where tittle like '_ello%';+------+--------------+| uid  | tittle       |+------+--------------+|    0 | Hello World! |+------+--------------+79 rows in set (0.00 sec)

通配符使用技巧

1. 不要过度使用通配符
2. 通配符尽量不要放在搜索模式的开头，否则会很慢。
3. 要注意通配符的位置。