MySQL数据表中内容大小写区分的设置

MySQL数据表中内容大小写区分的设置

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)