如何使用多个触发器？

Question

DROP TRIGGER IF EXISTS N2Trigger


CREATE TRIGGER N2Trigger 
ON dbo.Date
FOR INSERT, DELETE 
AS 
BEGIN 
    SELECT 'Inserted Datebase' as MESSAGE
    SELECT 'Deleted Database' as MESSAGE
END

DELETE FROM dbo.[Date] WHERE ID = 1 

Here is my code I just want when I use insert statement return 'Inserted Datebase' as MESSAGE

When I use delete statement return 'Deleted Database' as MESSAGE

Answer 1

The easiest way to check what action fired the trigger is to inspect the inserted and deleted pseudo-tables. If the trigger is only on DELETE / INSERT and not on update, then the logic is simply:

CREATE TRIGGER dbo.trFlarb ON dbo.flarb
  FOR INSERT, DELETE
  AS
  BEGIN
    IF EXISTS (SELECT 1 FROM inserted)
    BEGIN
      SELECT 'Inserted.';
    END

    IF EXISTS (SELECT 1 FROM deleted)
    BEGIN
      SELECT 'Deleted.';
    END
  END

• Example db<>fiddle

Now, of course, Marc is right: triggers aren't for returning or printing output. This is just a demonstration that you can use those checks to then perform whatever logic you need to perform in the event of either action.

That said, if you have two distinctly different things you want to do depending on whether it's an insert or a delete, why not just create two separate triggers?

CREATE TRIGGER dbo.tr_I_Flarb ON dbo.flarb
  FOR INSERT
  AS
  BEGIN
      SELECT 'Inserted.';
  END
GO

CREATE TRIGGER dbo.tr_D_Flarb ON dbo.flarb
  FOR DELETE
  AS
  BEGIN
      SELECT 'Deleted.';
  END
GO