MEL Specify schema browser

DROP TRIGGER IF EXISTS exchangein_before_insert;
 
DELIMITER $$
 
CREATE TRIGGER exchangein_before_insert BEFORE INSERT ON exchangein
FOR EACH ROW
  BEGIN
    DECLARE var_gift_number INTEGER(11);
        DECLARE var_exchangein_number INTEGER(11);
 
        IF isnull(@DISABLE_TRIGGER) THEN
            SELECT MAX(GiftNumber)
            INTO var_gift_number
            FROM gift;
 
            SELECT MAX(Text1)
            INTO var_exchangein_number
            FROM exchangein;
 
            IF var_gift_number>=var_exchangein_number THEN
                SET NEW.Text1=LPAD(var_gift_number+1, 4, '0');
            ELSE
                SET NEW.Text1=LPAD(var_exchangein_number+1, 4, '0');
            END IF;
        END IF;
  END
 
DELIMITER ;