You can create a unique index on the column that will enforce the unique
constraint.
Reid Lai wrote in message <35F8BFD4.9EBF1D95_at_hk.super.net>...
>You should use BEFORE INSERT trigger to do so instead of constraint.
>
>Roy Smith wrote:
>
>> I've got a column which I want to allow to be null, but if there is a
>> value in it, I want to ensure that value is unique amongst the non-null
>> entries. Can a constraint be used to do this?
>>
>> --
>> Roy Smith <roy_at_popmail.med.nyu.edu>
>> New York University School of Medicine
>
>
>
Received on Tue Sep 15 1998 - 10:46:16 CDT
