unique constraint with significant nulls?

[Mike Blackwell <mike.blackwell@xxxxxxx>]

How would one go about building a multi-column unique constraint where null is a significant value, eg. (1, NULL) <> (2, NULL)?

I see a number of references to not being able to use an index for this, but no mention of an alternative.  Any pointers would be appreciated

__________________________________________________________________________________
Mike Blackwell | Technical Analyst, Distribution Services/Rollout Management | RR Donnelley
1750 Wallace Ave | St Charles, IL 60174-3401
Office: 630.313.7818
Mike.Blackwell@xxxxxxx
http://www.rrdonnelley.com