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Create unique constraint with null columns
..., menu_id, recipe_id)
WHERE menu_id IS NOT NULL;
CREATE UNIQUE INDEX favo_2col_uni_idx ON favorites (user_id, recipe_id)
WHERE menu_id IS NULL;
This way, there can only be one combination of (user_id, recipe_id) where menu_id IS NULL, effectively implementing the desired constraint.
Possible dra...
Instantiating object of type parameter
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answered Nov 18 '08 at 20:24
ericksonerickson
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256
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...ttp://visualstudiogallery.msdn.microsoft.com/aacbc77c-4ef6-456f-80b7-1f157c2909f7/
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