> :: This is the same behaviour as when you change a domain so it
> :: has a default value. The column may contain nulls. Good
> :: admin tools realise this and ask if you want to update the
> :: field. Likewise it's up to you before creating a unique
> :: index to check for duplicates. It's not just the presence of
>
> I understand this, but my field did not have any duplicates. The only
> duplicate was "null" which is not a value and therfore should not be
> considered.
>
> :: null values it's duplicates of any kind.
>
> I didn't have any duplicates.
>
> :: I've never considered this a bug - just an administrative
> :: task to carry out when you are (re)designing your database.
> :: select mynewunique, count(*) from mytable group by
> :: mynewunique will show you straight away if what you are
> :: proposing is sensible given the current state of that table.
>
> In fact to be sure, I just ran this now and there we no duplicates, only
> null. Null has 1213 occurrances, everything else had 1.
>

that's 1213 duplicates as far as a unique index is concerned
Alan