SQL delete rows when no more row on other table

I'm trying to create a trigger on phpmyadmin. I want to delete all rows from table NEXT_GAME as soon as there is no more row in WAITING_ROOM.

I tried the following solution :

CREATE TRIGGER delete_begin_date AFTER DELETE
ON NEXT_GAME FOR EACH ROW
BEGIN
    IF NOT EXISTS (SELECT * FROM WAITING_ROOM) THEN
        DELETE FROM NEXT_GAME;
    END IF;
END

I got the following error :

You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '' at line 5

What did I do wrong ?

Solution

You need a specific delimiter to tell MySQL that the next ; doesn't ends the CREATE TRIGGER statement.

DELIMITER $$
CREATE TRIGGER delete_begin_date AFTER DELETE
ON NEXT_GAME FOR EACH ROW
BEGIN
    IF NOT EXISTS (SELECT * FROM WAITING_ROOM) THEN
        DELETE FROM NEXT_GAME;
    END IF;
-- vv----------------------- Notice this
END$$
DELIMITER ; -- switch back to the regular ;