MySQL 查询字段时，区分大小写

设置排序规则：

区分大小写的查询：

mysql> select * from user;
+----+----------+-----------+------+------+
| id | username | loginname | pwd  | sex  |
+----+----------+-----------+------+------+
|  1 | 小明     | xiaoming  | 123  | 1    |
|  2 | 管理员   | Admin     | 123  | 1    |
+----+----------+-----------+------+------+
2 rows in set (0.00 sec)

mysql> select * from user where loginname="Admin";
+----+----------+-----------+------+------+
| id | username | loginname | pwd  | sex  |
+----+----------+-----------+------+------+
|  2 | 管理员   | Admin     | 123  | 1    |
+----+----------+-----------+------+------+
1 row in set (0.00 sec)

mysql> select * from user where loginname="admin";
Empty set (0.00 sec)