How to set a default value for one column in SQL based on another column

Question

I\'m working with an old SQL 2000 database and I don\'t have a whole lot of SQL experience under my belt. When a new row is added to one of my tables I need to assign a defa

Answer 1

So, for example, in a TAG table (where tags are applied to posts) if you want to count one tag as another...but default to counting new tags as themselves, you would have a trigger like this:

CREATE TRIGGER [dbo].[TR_Tag_Insert]
   ON  [dbo].[Tag]
   AFTER INSERT
AS 
BEGIN
   SET NOCOUNT ON;

   UPDATE dbo.Tag 
   SET [CountAs] = I.[ID]
   FROM INSERTED AS I
   WHERE I.[CountAs] IS NULL
   AND dbo.Tag.ID = I.ID
END