创建MySQL函数时出错（1064）

Question

phpMyAdmin: 3.5.7
MySQL: 5.5.29

I want users to be able to compile several different lists from posts in the database. The following function is supposed to be used to add a post to one such list. It checks if the list ID supplied by the user matches with the given user id, then checks if the list is not full, then adds post to list.

DELIMITER //

CREATE FUNCTION addToFav(inputKid INT, inputUid INT, listID INT, listLimit INT)
RETURNS VARCHAR(300)

BEGIN
DECLARE resultMsg VARCHAR(300);
DECLARE listExists INT; SET listExists = (SELECT COUNT(*) FROM fav_lists WHERE fav_list_id=listID AND uid=inputUid AND active=1);

IF 1 > listExists THEN SET resultMsg = 'LIST NON-EXISTANT';
ELSE 
    DECLARE listSize INT; 
        SET listSize = (SELECT COUNT(*) FROM fav_links WHERE fav_list_id=listID AND active=1);
    IF listSize = listLimit THEN SET resultMsg = 'LIST FULL';
        ELSE IF listSize > listLimit THEN SET resultMsg ='dbErr: LIST OVER LIMIT';
        ELSE 
            REPLACE INTO fav_links (kid, fav_list_id, active) VALUES (inputKid, listID, 1);
            SET resultMsg ='SUCCESS';
        END IF;
END IF;


RETURN resultMsg;
END //

DELIMITER ;

I enter this code into phpMyAdmin's SQL console, it returns

#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'DECLARE listSize INT; SET listSize = (SELECT COUNT(*) FROM fav_links W' at line 10

Now, should I move the "faulty" line up, the code looks like this:

DELIMITER //

CREATE FUNCTION addToFav(inputKid INT, inputUid INT, listID INT, listLimit INT)
RETURNS VARCHAR(300)

BEGIN
DECLARE listSize INT; SET listSize = (SELECT COUNT(*) FROM fav_links WHERE fav_list_id=listID AND active=1);
DECLARE resultMsg VARCHAR(300);
DECLARE listExists INT; SET listExists = (SELECT COUNT(*) FROM fav_lists WHERE fav_list_id=listID AND uid=inputUid AND active=1);
[...]

This version points to the same error, but on another line:

#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'DECLARE resultMsg VARCHAR(300); DECLARE listExists INT; SET listExists = (SELEC' at line 6

This leads me to believe the problem might be caused by faulty use of the delimiter, but that is all I have got right now. PhpMyAdmin has a delimiter field after the SQL insertion field, which I have tried leaving empty, populating with ; and with // , none of which made a difference.

What might cause this issue, and how do I fix it?

Answer 1

You should keep variable declarations at the top. Also I took the freedom to rewrite some code:

DELIMITER //

CREATE FUNCTION addToFav(inputKid INT, inputUid INT, listID INT, listLimit INT)
RETURNS VARCHAR(300)

BEGIN
DECLARE resultMsg VARCHAR(300);
DECLARE listSize INT; 

IF (NOT EXISTS (SELECT 1 FROM fav_lists WHERE fav_list_id=listID AND uid=inputUid AND active=1)) THEN 
    SET resultMsg = 'LIST NON-EXISTANT';
ELSE 
    SELECT COUNT(*) INTO listSize FROM fav_links WHERE fav_list_id=listID AND active=1;
    IF (listSize = listLimit) THEN 
        SET resultMsg = 'LIST FULL';
    ELSEIF (listSize > listLimit) THEN 
        SET resultMsg ='dbErr: LIST OVER LIMIT';
    ELSE 
        BEGIN
            REPLACE INTO fav_links (kid, fav_list_id, active) VALUES (inputKid, listID, 1);
            SET resultMsg ='SUCCESS';
        END;
    END IF;
END IF;

RETURN resultMsg;
END //

DELIMITER ;

Don't use COUNT(*) if you only want to know if something exists.

Answer 2

Try below code, In MySQL , while using ELSE IF Code there doesn't given space between ELSE and IF`. Also Declare variables at the top

DELIMITER //

CREATE FUNCTION addToFav(inputKid INT, inputUid INT, listID INT, listLimit INT) RETURNS VARCHAR(300)

BEGIN

    DECLARE resultMsg VARCHAR(300);
    DECLARE listExists INT; 
    DECLARE listSize INT; 

    SET listExists = (SELECT COUNT(*) FROM fav_lists WHERE fav_list_id=listID AND uid=inputUid AND active=1);

    IF (1 > listExists) THEN 
        SET resultMsg = 'LIST NON-EXISTANT';
    ELSE 
        SET listSize = (SELECT COUNT(*) FROM fav_links WHERE fav_list_id=listID AND active=1);
            IF listSize = listLimit THEN 
                SET resultMsg = 'LIST FULL';
            ELSEIF listSize > listLimit THEN 
                SET resultMsg ='dbErr: LIST OVER LIMIT';
            ELSE 
                REPLACE INTO fav_links (kid, fav_list_id, active) VALUES (inputKid, listID, 1);
                SET resultMsg ='SUCCESS';
            END IF;
    END IF;

RETURN resultMsg;
END //

DELIMITER ;