Re: Way to create unique constraint in Postgres even with null columns - Mailing list pgsql-general

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;