mysql stored procedure login - mysql

Question

I am using mysql and have a procedure for login authentication,
CREATE PROCEDURE CheckPassword (IN username CHAR(8),IN password_p VARCHAR(20), OUT yes_no char(1))
BEGIN
IF EXISTS(SELECT * FROM USER WHERE USER_ID = username AND password = password_p) then
set yes_no = '0';
ELSE
set yes_no = '1';
END IF;
END;
But it mysql warned that having error when creatinng the procedure, it say have the error i nfor line 4, it is the line of "set yes_no = '0';"? I have try this way too,
CREATE PROCEDURE CheckPassword (IN username CHAR(8),IN password_p VARCHAR(20), OUT yes_no char(1))
BEGIN
IF EXISTS(SELECT * FROM USER WHERE USER_ID = username AND password = password_p) then
select '0' into yes_no;
ELSE
select '1' into yes_no;
END IF;
END;
Didn't work too, is that a must to use delimeter when create procedure? and can u tell me statement of calling this procedure,

Answer 1

I think that the problem was that USER is a reserved word. Also, I suggest you use a function, not a procedure (you just want a value to be returned).
This function works:
DELIMITER ||
CREATE FUNCTION CheckPassword (username VARCHAR(8), password_p VARCHAR(20))
RETURNS BOOL
NOT DETERMINISTIC
READS SQL DATA
BEGIN
RETURN EXISTS (SELECT username FROM `USER` WHERE USER_ID = username AND password = password_p);
END;
||
DELIMITER ;
SELECT CheckPassword('a','b');

Answer 2

Try this:
CREATE PROCEDURE `IsUserPasswordValid`(
IN username varchar(50),
IN password_p VARCHAR(20),
OUT yes_no int
)
BEGIN
SELECT count(*) INTO yes_no
FROM USER u
WHERE u.USER_ID = username && u.password = password_p;
END
If it returns 1 then user is valid.