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help / color / mirror / Atom feedFrom: Tim Landscheidt <tim@tim-landscheidt.de>
To: pgsql-sql@postgresql.org
Subject: Re: FOREIGN KEY Reference on multiple columns
Date: Wed, 24 Sep 2014 18:02:34 +0000
Message-ID: <87y4t8rj5x.fsf@passepartout.tim-landscheidt.de> (raw)
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"Weiss, Jörg" <J.Weiss@dvz-mv.de> wrote:
> I mean b must equal to c1 in the "other_table" where c2 has a certain value (for example c2 ).
> For my first example:
> CREATE TABLE parm
> (
> complex varchar(20) NOT NULL,
> para varchar(50) NOT NULL,
> sort int4 NOT NULL DEFAULT 10,
> value varchar(50) NULL,
> CONSTRAINT parm_pkey PRIMARY KEY (complex, para, sort)
> )
> Table user
> CREATE TABLE user
> (
> name varchar(20) NOT NULL,
> type integer NULL
> )
> In this case "type" of table user must equal to "value" of table "parm" and "para" must be "login_user" (for example)
> [...]
You can achieve that by duplicating the para column to the
table user, adding a foreign key that matches both columns
to table parm and checks in table user whether para is
"login_user". That doesn't work for NULLable columns,
though.
Tim
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To: pgsql-sql@postgresql.org
Cc: tim@tim-landscheidt.de
Subject: Re: FOREIGN KEY Reference on multiple columns
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