流程控制的使用CASE 语句用法

CASE 语句

CASE case_value
WHEN when_value THEN statement_list
[WHEN when_value THEN statement_list]...
[ELSE statement_list ]
END CASE

eg:

DELIMITER &&
CREATE PROCEDURE pro_user6(IN bookId INT)
BEGIN
SELECT COUNT(*) INTO @num FROM t_user WHERE id=bookId;
CASE @num
 WHEN 1 THEN UPDATE t_user SET userName='java12345' WHERE id=bookId;
 WHEN 2 THEN INSERT INTO t_user VALUES(NULL,'2312312','2321312');
 ELSE INSERT INTO t_user VALUES(NULL,'231231221321312','2321312321312');
END CASE ;
END 
&&
DELIMITER 

CALL pro_user6(5);