Mysql select默认不区分大小写

转自：http://blog.chinaunix.net/u/29134/showart_355336.html

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。