title: Instead of trigger to update primary key
body: <p>Long time reader, first time poster ;-)</p>
  
  <p>I'm implementing a system based on an old system. The new system uses SQL Server 2008 and my problem comes when trying to insert new items in the main table. This will happen in two ways: It may be imported from the existing system (1) or may be created in the new system (2).</p>
  
  <p>In case (1) the item already has an ID (int) which I would like to keep. In case (2) the ID will not be filled in and I'd like to generate an ID which is +1 of the maximum current value in the table. This should of course also work for inserts of mutiple rows.</p>
  
  <p>As far as I can see, the solution will be to create a INSTEAD OF TRIGGER, but I can't quite figure out how this is done. Can anyone give me a hint or point me in the direction of how this can be done?</p>
  
  <p>Chris</p>