Unique constraint column using nvarchar(max)??

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Unique constraint column using nvarchar(max)??

WWDMark

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November 22, 2012 at 7:31 am

#266320

Can anyone help please?
Can I use nvarchar(max) when creating a unique constraint on a column and if not (which I suspect) why not??
Cheers.
MCITP
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e4d4 SSCertifiable Points: 5777 More actions · Answer 1

Why do you want to do this?

You can't because of eg. limitations of internal structures of DB

WWDMark Hall of Fame Points: 3157 More actions · Answer 2

Done a bit more digging and come up with an answer: "the maximum size for a column that is included in a unique constraint is NVARCHAR(450) or 900 bytes."

That makes sense now! The question actually came up as part of a mock paper I was given to prep for my MS 70-433 exam (DB Development) and I just needed to understand the logic behind it.

Thanks though.

MCITP
MCTS - E-Business Card
Twitter: WWDMark

Try not! Do or do not, there is no try

email: info@weekendwebdesign.co.uk
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