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I am designing a database for a custom software application. The part I am focused on now is the ability to add custom questions to ask users.

I want to ensure that each user can only answer a question once. In this case, a user is a 'Provider'. How do I ensure each user only answers a question once?

database mockup

markp-fuso
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asked Sep 11, 2017 at 18:27
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1 Answer 1

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A unique constraint on Answers (questionid, providerid) was needed, as suggested by Balazs Papp.

As explicitly pointed out by Andriy M this should be a composite key.

I had to look up composite keys, as I was unfamiliar. Thanks so much to everyone for helping and responding so quickly.

Paul White ♦
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answered Sep 11, 2017 at 20:19

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