Today, when I used mysql data for a login verification, I found that the user name queried in the database would not be case-sensitive when logging in. Later, I found out the reason after Baidu.
MYSQL queries are case-insensitive by default, for example:
mysql> create table t1(
-> name varchar(10));
Query OK, 0 rows affected (0.09 sec)
mysql> insert into t1 values('admin'),('Admin'),('ADmin');
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:
+------+ | name | +------+ | you | | You | | YOU | +------+ 3 rows in set (0.00 sec) mysql> select * from t1 where name = Admin'; +------+ | name | +------+ |admin | |Admin | |ADmin | +------+ 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:
|
如果你只是想在SQL语句中实现的话:
mysql> select * from t1 where name = binary 'Admin';
+------+
| name |
+------+
|Admin |
+------+
1 row in set (0.02 sec)
mysql> select * from t1 where name = binary 'admin';
+------+
| name |
+------+
|admin |
+------+
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