mysql case实例：在存储过程中使用CASE WHEN语句

本节学习下mysql中case when语句的用法，看看在存储过程中如何调用。
代码如下：

mysql> delimiter $$
mysql> CREATE PROCEDURE myProc(customer_status VARCHAR(10))
    -> BEGIN //创建mysql存储过程
    ->
    ->     CASE customer_status //case when语句用法
    ->          WHEN 'PLATINUM'  THEN
    ->               select 'PLATINUM';
    ->
    ->          WHEN 'GOLD' THEN
    ->               select 'GOLD';
    ->
    ->          WHEN 'SILVER' THEN
    ->               select 'SILVER';
    ->
    ->          WHEN 'BRONZE' THEN
    ->               select 'BRONZE';
    ->     END CASE;
    -> END$$
Query OK, 0 rows affected (0.00 sec)

mysql> delimiter ;
mysql> call myProc('BRONZE'); //调用存储过程
+--------+
| BRONZE |
+--------+
| BRONZE |
+--------+
1 row in set (0.00 sec)

Query OK, 0 rows affected (0.00 sec)

mysql> call myProc('GOLD'); //调用存储过程
+------+
| GOLD |
+------+
| GOLD |
+------+
1 row in set (0.00 sec)

Query OK, 0 rows affected (0.00 sec)

mysql> drop procedure myProc; //删除mysql存储过程
Query OK, 0 rows affected (0.00 sec)