Check if the trigger was fired by INSERT or DELETE

Question

I know this is the easiest question you can find on this website but I wasn't able to find its answer on the internet.

How to check if the trigger was fired by an INSERT or DELETE?

Example

CREATE TRIGGER [dbo].[TestTrigger]
On [dbo].[Table1]
AFTER INSERT, DELETE
AS
    --if save
    --do some work

    --else if delete
    --do some work other work

I want to do some work if it's an insert and some other work if it is a delete.

Please provide a code snippet for the same.

Answer 1

As long as the trigger is only for insert/delete:

IF EXISTS (SELECT 1 FROM inserted)
   -- I am an insert
ELSE
   -- I am a delete

And in fact if you are doing things based on a join to inserted/deleted, it can be even simpler:

-- do something for an insert
-- this will only actually do anything when it's an insert
INSERT dbo.somewhereElse SELECT whatever, 'insert'
  FROM dbo.sourceTable AS s
  INNER JOIN inserted AS i ON s.id = i.id;

-- do something for a delete
-- this will only actually do anything when it's a delete
INSERT dbo.somewhereElse SELECT whatever, 'delete'
  FROM dbo.sourceTable AS s
  INNER JOIN deleted AS d ON s.id = d.id;

If you add the update action to the trigger, the logic gets more complex, of course:

IF EXISTS (SELECT 1 FROM inserted)
BEGIN
  IF EXISTS (SELECT 1 FROM deleted)
  BEGIN
    -- I am an update
  END
  ELSE
  BEGIN
    -- I am an insert
  END
END
ELSE
BEGIN
  -- I am a delete
END

Answer 2

_{Since my comment went unanswered, I have converted it to an answer.}

I want to do some work if it's an insert and some other work if it is a delete.

You could create separate triggers, one for insert, and one for delete:

CREATE TRIGGER dbo.Table1_AI
ON dbo.Table1
AFTER INSERT
AS
... insert-specific actions

CREATE TRIGGER dbo.Table1_AD
ON dbo.Table1
AFTER DELETE
AS
... delete-specific actions