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MYSQL在默认的情况下查询不区分大小写

时间:2021-07-01 10:21:17 帮助过:42人阅读

MYSQL在默认的情况下查询是不区分大小写的,例如: mysql create table t1( - name varchar(10));Query OK, 0 rows affected (0.09 sec)mysql insert into t1 values('you'),('You'),('YOU');Query OK, 3 rows affected (0.05 sec)Records: 3 Duplicates: 0

MYSQL在默认的情况下查询是不区分大小写的,例如: mysql> create table t1(     -> name varchar(10)); Query OK, 0 rows affected (0.09 sec) mysql> insert into t1 values('you'),('You'),('YOU'); Query OK, 3 rows affected (0.05 sec) Records: 3  Duplicates: 0  Warnings: 0 对这个表,缺省情况下,下面两个查询的结果是一样的:
mysql> select * from t1 where name = 'you'; +------+ | name | +------+ | you  | | You  | | YOU  | +------+ 3 rows in set (0.00 sec) mysql> select * from t1 where name = 'YOU'; +------+ | name | +------+ | you  | | You  | | YOU  | +------+ 3 rows in set (0.00 sec)
如果想让MYSQL知道你输入的字母是大写还是小写的,修改表:
mysql> alter table t1 change name name varchar(10) binary; Query OK, 3 rows affected (0.20 sec) Records: 3 Duplicates: 0 Warnings: 0 mysql> select * from t1 where name = 'you'; +------+ | name | +------+ | you | +------+ 1 row in set (0.00 sec) mysql> select * from t1 where name = 'YOU'; +------+ | name | +------+ | YOU | +------+ 1 row in set (0.00 sec)
如果你只是想在SQL语句中实现的话: mysql> select * from t1 where name = binary 'YOU'; +------+ | name | +------+ | YOU  | +------+ 1 row in set (0.02 sec) mysql> select * from t1 where name = binary 'you'; +------+ | name | +------+ | you  | +------+ 1 row in set (0.00 sec)
 
如果不想这么麻烦而想服务一开启就让大小写一致的话: 可以修改my.ini或者my.cnf [mysqld]  lower_case_table_names=1 (0:区分;1:不区分) 然后重启MYSQL服务。 mysql> show variables like '%case_table%'; +------------------------+-------+ | Variable_name          | Value | +------------------------+-------+ | lower_case_table_names | 1     | +------------------------+-------+ 1 row in set (0.00 sec) 注:WINDOWS系统不用修改,系统默认就是1 LINUX 系统默认是0。因为LINUX下的脚本都是区分大小写的。 

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