Trigger in MySQL

Question

I am trying to create a trigger wherein it will insert a new row to a ADMIN_EMAIL_DOMAINS table.

CREATE TRIGGER email_domain_insert AFTER INSERT ON USERS
FOR EACH ROW 
BEGIN
    IF NOT EXISTS (SELECT * FROM (SELECT DISTINCT SUBSTRING_INDEX(USR_EMAIL, '@', -1) as domain FROM USERS) as a WHERE a.domain = SUBSTRING_INDEX(NEW.USR_EMAIL, '@', -1)) THEN
        INSERT INTO ADMIN_EMAIL_DOMAINS (DOMAIN_NAME, VISIBLE) VALUES (SUBSTRING_INDEX(NEW.USR_EMAIL, '@', -1), 1);
    END IF;
END //

What I would like to do is everytime I create a new user, i would check its email extension and then insert it to ADMIN_EMAIL_DOMAINS table if that DOMAIN_NAME is not yet existing.

My problem is it has an SQL error when i tried to execute it

#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 '' at line 5 

Am I missing something?

Answer 1

I could suggest you another way - make field DOMAIN_NAME as unique and try to insert new domains into the table ADMIN_EMAIL_DOMAINS with IGNORE option, eg -

DELIMITER $$

CREATE TRIGGER email_domain_insert
  AFTER INSERT
  ON users
  FOR EACH ROW
BEGIN
  INSERT IGNORE INTO ADMIN_EMAIL_DOMAINS (DOMAIN_NAME, VISIBLE) VALUES (SUBSTRING_INDEX(NEW.USR_EMAIL, '@', -1), 1);
END    

DELIMITER ;