From: | Sean Davis <sdavis2(at)mail(dot)nih(dot)gov> |
---|---|
To: | "Andrei Bintintan" <klodoma(at)ar-sd(dot)net> |
Cc: | <pgsql-sql(at)postgresql(dot)org> |
Subject: | Re: Constraint on 2 column possible? |
Date: | 2005-01-27 12:08:03 |
Message-ID: | 18D0F33A-705C-11D9-8FBF-000D933565E8@mail.nih.gov |
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Thread: | |
Lists: | pgsql-sql |
On Jan 27, 2005, at 6:44 AM, Andrei Bintintan wrote:
> Hi,
>
> I have a table:
> CREATE TABLE werke1(
> id SERIAL,
> id_hr int4 NOT NULL,
> id_wk int4 NOT NULL
> );
>
> CREATE TABLE contact(
> id SERIAL,
> type varchar(20),
> );
>
It looks like you want a two-column primary key for table contact and
then you can reference contact(id,type).
Sean
>
>
> Now id_hr and id_wk are all referencing the same table contact(id). In
> the contact table I have another column called type.
> How can I write a constraint that checks that id_hr references
> contact(id) and the contact(type='t1')
> and that id_wk references contact(id) and the contact(type='t2').
>
> More explicit: the id_hr shows to the id from contact, and this line
> from contact must have the line type='t1'. The same for id_wk just the
> type is another.
>
> I can write:
> CREATE TABLE werke1(
> id SERIAL,
> id_hr int4 NOT NULL references contact(id),
> id_wk int4 NOT NULL references contact(id)
> );
> but how do I check also the type column?
>
> Best regards,
> Andy.
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