【MYSQL】查询不区分大小写

时间:2022-04-16 03:57:08

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。 

http://www.blogjava.net/brock/archive/2009/04/17/266168.html