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unique constraint on 2 columns - Mailing list pgsql-general

From Jonathan Vanasco
Subject unique constraint on 2 columns
Date
Msg-id 16BE9D41-D328-4F9F-A7D2-623388239D1E@2xlp.com
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Responses Re: unique constraint on 2 columns  (Jorge Godoy <jgodoy@gmail.com>)
Re: unique constraint on 2 columns  (Tom Lane <tgl@sss.pgh.pa.us>)
Re: unique constraint on 2 columns  (Scott Marlowe <smarlowe@g2switchworks.com>)
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I need a certain unique constraint in pg that i can't figure out.

Given:

    create table test_a (
        id serial ,
        name_1 varchar(32) ,
        name_2 varchar(32)
    );

I need name_1 and name_2 to both be unique so that:
    name_1 never appears in name_1 or name_2
    name_2 never appears in name_2 or name_1


a standard 2 column unique index / constraint will not accomplish this.

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