Question

I´m trying to create a trigger on MySQL but I´m having a syntax problem, which I was not able to find. If someone more experience could help me it would be great (it´s the first time I use MySQL!)…

The reason why I´m creating this trigger is for deleting all the orphan “labels”, which has a many-to-many relation with “service_descriptor” (this two entities are linked by service_labels).

The code I have is:

CREATE TRIGGER `trg_delete_orphan_label` AFTER DELETE 
FOR EACH ROW ON `restdb`.`service_labels`  
  DELETE FROM `restdb`.`labels`
   WHERE EXISTS (SELECT *
                   FROM old D 
              LEFT_JOIN `restdb`.`service_labels` SL ON SL.`id_label` = D.`id_label` 
                                                    AND D.`id_service` = SL.`id_service`
                  WHERE SL.`id_label` IS NULL
                        `restdb`.`labels`.`id` = D.SL.`id_label`); 

Thanks in advance !

Answer 1

Thanks everyone … I´ve finaly solved it because of your help…

In the end the work is:

CREATE TRIGGER trg_delete_orphan_label AFTER DELETE ON restdb.service_descriptor
FOR EACH ROW
DELETE FROM restdb.labels
WHERE id NOT IN (
SELECT restdb.service_labels.id_label
FROM restdb.service_labels );