MySQL Error 1064: You have an error in your SQL syntax

    DELIMITER //
    CREATE FUNCTION fnc_credit_custstatus
    RETURNS VARCHAR(6) DETERMINISTIC
     BEGIN
     DECLARE custstatus VARCHAR(6);
     IF CustCredit>='1000',THEN SET custstatus='VIP';
     ELSEIF CustCredit<'1000',THEN SET custstatus='NONVIP';
   END IF;
   RETURN (custstatus);
   END//
   DELIMITER ;

Query:

CREATE function fnc_credit_custstatus returns varchar(6) deterministic 
begin DECLARE custstatus VARCHAR(6); if CustCredit>='1000...

Error Code: 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 'varchar(6) deterministic begin DECLARE custstatus VARCHAR(6); if CustCredit>=' at line 2

Try remove comma

    DELIMITER //
        CREATE FUNCTION fnc_credit_custstatus
        RETURNS VARCHAR(6) DETERMINISTIC
         BEGIN
         DECLARE custstatus VARCHAR(6);
         IF CustCredit>=1000 THEN SET custstatus='VIP';
         ELSEIF CustCredit<1000 THEN SET custstatus='NONVIP';
       END IF;
       RETURN (custstatus);
       END//
       DELIMITER ;

(and use proper comparision data type)