Re: Establishing a primary key

From: Scott Marlowe <smarlowe(at)g2switchworks(dot)com>
To: Bob Pawley <rjpawley(at)shaw(dot)ca>
Cc: Postgresql <pgsql-general(at)postgresql(dot)org>
Subject: Re: Establishing a primary key
Date: 2007-06-22 20:38:12
Message-ID: 467C3334.7080108@g2switchworks.com
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Bob Pawley wrote:
> I have numerous entries in a column of table 1, some of which are
> duplicated.
>
> I need to transfer this information to table 2 so that I have column
> that can be used as a primery key.
>
> Any help is appreciated.

So, I take it you're wanting to have this so that table 1 stays as it
is, and table 2 gets the entries from table 1 made unique, and becomes
the parent of table 1?

If that's the case, you want something like this:

create table2 as select distinct idcolumn from table1;
alter table2 add primary key (idcolumn);
alter table1 add foreign key (idcolumn) references table2(idcolumn);

I think that's about right.

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