jfogel (6/27/2012)
Toreador (6/27/2012)
tim.bearne (6/27/2012)
The fact that you can get an index made to support a completely different constraint is irrelevant.No it's not. Just because it is created for one purpose doesn't mean that it can't achieve a different purpose as well. An index created to support a unique constraint will also support the foreign key constraint, even though that's not why it was created.
But that wasn't the point of the question.
How do you know that for certain when you answer it? If #2 had been correct and the answer had stated that you could create a Uniqueness constraint and get a Unique Index created that would also support the foreign key, then a bunch of other folks would be crying foul.
Sorry Hugo, normally I enjoy your questions, and when I get them wrong, I still learn something. Knowing that the answer could be considered to be either #1 or #2 depending is just a little upsetting.