From: Martijn Tonies
Date: December 28 2004 9:27pm
Subject: Re: unique key <-> primary key
List-Archive: http://lists.mysql.com/mysql/177778
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Hello,

> I have two tables, seemigly very similar setup; the primary key is the
> combination of two columns. With mysqldump, however, the table
> definition of the two tables looks different.
>
> Mysqldump on table 1 says
>     ...
>     UNIQUE KEY HONstid (HONstid,HONname)
> whereas on table 2 it says
>     ...
>     PRIMARY KEY  (IMstid,IMfnum)
>
> What is the difference? Is there any?

A table can have only 1 primary key, but multiple unique constraints.

With regards,

Martijn Tonies
Database Workbench - developer tool for InterBase, Firebird, MySQL & MS SQL
Server
Upscene Productions
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