Insert Update trigger how to determine if insert or update

I need to write an Insert, Update Trigger on table A which will delete all rows from table B whose one column (say Desc) has values like the value inserted/updated in the table A's column (say Col1). How would I go around writing it so that I can handle both Update and Insert cases. How would I determine if the trigger is executed for an update or insert.

From stackoverflow

• If it's MS SQL Server, then IF EXISTS (SELECT * FROM DELETED) tells you if it's an update. You only have rows in DELETED on update, bt there are always rows in INSERTED.

  Look for "inserted" in CREATE TRIGGER

  MSIL : Thanks for the reply - Got everything I needed to know. I agree I must have added that I need to do it for SQL Server.