MySQL: Try to Port a Trigger from SQL Server

Question

Here, there's a sample of a trigger with "INSTEAD OF UPDATE" clause:

CREATE TRIGGER [dbo].[Test_PTA_Table_Update_trg]
-- ALTER TRIGGER [dbo].[Test_PTA_Table_Update_trg]
   ON  [dbo].[Test_PTA_Table]
   INSTEAD OF UPDATE
AS
   SET NOCOUNT ON
   DECLARE @key int
   SET @key = (SELECT TestTablePK FROM Inserted)

   UPDATE Test_PTA_Table
      SET DateEnd = GetDate(), DateReplaced = GetDate()
      WHERE TestTablePK = @key

   INSERT INTO dbo.Test_PTA_Table
   (TestTableText, DateCreated, DateEffective, OperatorCode, DateReplaced)
   (SELECT TestTableText, GetDate(), GetDate(), OperatorCode, NULL
FROM Inserted)

I'm trying to port the principle to MySQL:

DELIMITER ;;

DROP TRIGGER IF EXISTS attribut_trigger_update_before;

CREATE TRIGGER attribut_trigger_update_before
BEFORE UPDATE ON attribut
  FOR EACH ROW BEGIN
    INSERT INTO attribut SET 
      id_origine      = OLD.id_origine,
      date_v_creation = OLD.date_v_creation,
      date_v_debut    = OLD.date_v_debut,
      date_v_fin      = OLD(),
      importance      = OLD.importance,
      description     = OLD.description,
      valeur          = OLD.valeur,
      abbreviation    = OLD.abbreviation;
  END;;

DELIMITER ;;

But it doesn't work.

mysql> update produit set importance=3;
ERROR 1442 (HY000): Can't update table 'produit' in stored function/trigger because it is already used by statement which invoked this stored function/trigger.
mysql> 

Any idea how to do this?

Answer 1

This has been discussed before by others

• Making a column immutable in MySQL
• What are some good methods of structuring a MySQL audit trail to be both immutable, and perform well for usage?

Your question is a little different in this instance. You may have to experiment with INSERT IGNORE or REPLACE for the desired effect.

You may need to also experiment with disabling the trigger midstream : Disable trigger for just one table