HERE IT IS . . . . .

  CREATE TABLE aaaa (
    aaa char (  3 )  NULL,
    bbb char (  3 )  NULL,
    zCount int NULL
   )
  GO

  CREATE  UNIQUE  INDEX zkey ON aaaa
    ( zCount )
  GO

  CREATE TRIGGER aaaaIns ON dbo.aaaa FOR INSERT  AS
  BEGIN
   /* No matter what is entered, the zCount will be set to the record
      count */
   IF (Select zCount from inserted) Is Not NULL
    update aaaa
    set zCount = (Select Count(*) from aaaa)
    where zCount = (Select zCount from inserted)
   ELSE
    update aaaa
    set zCount = (Select Count(*) from aaaa)
    where zCount Is Null
  END
  GO

  CREATE TRIGGER aaaaUpd ON dbo.aaaa FOR UPDATE  AS
  BEGIN
  /* If any attempt to change zCount to something other than the record count
     the transaction will be rolled back.  Keeping in mind that the insert 
     trigger will also trigger the update trigger */
  If (Select zCount from inserted)  (Select Count(*) from aaaa)
  BEGIN
     RAISERROR 600225 'Trigger aaaaUpd on table dbo.aaaa:  Not allowed to update
  zCount.
     ROLLBACK TRANSACTION
     RETURN
  END
  END
  GO

Name: John Holland
Email: john.holland@exim.gov