David Johnston wrote on 27.11.2011 23:18:
> Also, the index example above presumes you want RecipeId to be "Null-able"
> as opposed to MenuId as described in your original post.
>
Well of course that was a typo in my answer, it should have been:
CREATE UNIQUE INDEX Favorites_UniqueFavorite
ON (UserId, RecipeId)
WHERE MenuId IS NULL;