add trigger to prevent insert duplicate domain with status = 1

[Akhilesh1004]

No description provided.

[LeeLin2602]

Please provide SQL statements like below next time:

DELIMITER $$

CREATE TRIGGER before_insert_domains
BEFORE INSERT ON domains FOR EACH ROW
BEGIN
    IF NEW.status = 1 AND (
        SELECT COUNT(*)
        FROM domains
        WHERE domain = NEW.domain AND status = 1
    ) > 0 THEN
        SIGNAL SQLSTATE '45000'
        SET MESSAGE_TEXT = 'This domain has been registered';
    END IF;
END$$

DELIMITER ;