默认情况下mysql的对比条件是大小写不敏感的（latin1_general_ci)，所有不敏感的collate都以_ci结尾。
要让对比条件大小写敏感，需要将collate设置为以_cs或者_bin结尾（比如utf8_unicode_cs和utf8_bin）

检查当前的collate

你可以检测你的服务，数据库和连接的collate，通过：

mysql> show variables like '%collation%';
+----------------------+-------------------+
| Variable_name        | Value             |
+----------------------+-------------------+
| collation_connection | utf8_general_ci   |
| collation_database   | latin1_swedish_ci |
| collation_server     | latin1_swedish_ci |
+----------------------+-------------------+

你也可以检测表的collate，通过:

mysql> SELECT table_schema, table_name, table_collation 
       FROM information_schema.tables WHERE table_name = `mytable`;
+----------------------+------------+-------------------+
| table_schema         | table_name | table_collation   |
+----------------------+------------+-------------------+
| myschema             | mytable    | latin1_swedish_ci |

改变 collate

你可以改变数据库，表，或者列的collate为大小写敏感：

-- Change database collation
ALTER DATABASE `databasename` DEFAULT CHARACTER SET utf8 COLLATE utf8_bin;

-- or change table collation
ALTER TABLE `table` CONVERT TO CHARACTER SET utf8 COLLATE utf8_bin;

-- or change column collation
ALTER TABLE `table` CHANGE `Value` 
    `Value` VARCHAR(255) CHARACTER SET utf8 COLLATE utf8_bin;