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Re: UNIQUE KEY vs UNIQUE INDEX

From: mos (mos99fastmail.fm)
Date: Thu Jul 30 2009 - 11:26:48 CDT


At 09:13 AM 7/30/2009, b wrote:
>Are UNIQUE KEY & UNIQUE INDEX two ways of specifying the same thing? If
>not, what are the differences?
>
>Feel free to tell me to RTFM but please post manual chapters. I've been
>looking but haven't been able to find anything.

They are the same thing. If you meant "Primary Key" and "Unique Index"
then they too are basically the same except Primary Key is NOT NULL and the
optimizer will infer the primary key when doing RI joins if an index is not
specified.

There may be other subtle differences that others can comment on.

Mike

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