From: | "Hiroshi Inoue" <Inoue(at)tpf(dot)co(dot)jp> |
---|---|
To: | "Niall Smart" <niall(dot)smart(at)ebeon(dot)com> |
Cc: | <pgsql-sql(at)postgresql(dot)org> |
Subject: | RE: Problem with subquery in CHECK constraint. |
Date: | 2000-06-08 18:01:50 |
Message-ID: | EKEJJICOHDIEMGPNIFIJGEJMCBAA.Inoue@tpf.co.jp |
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Lists: | pgsql-sql |
> -----Original Message-----
> From: pgsql-sql-owner(at)hub(dot)org [mailto:pgsql-sql-owner(at)hub(dot)org]On
> Behalf Of Niall Smart
>
>
> CONSTRAINT TYPE_CD_OK CHECK (
> EXISTS (SELECT 1 FROM XREF WHERE
> XREF_GROUP = 'CUST_TYPE' AND
> XREF_CD = TYPE_CD)
> )
>
>
> > There seems to be more serious problems.
> > 1) The constraint is not only for the defined table but also
> for referenced
> > tables in the subquery.
>
> I don't understand what you mean -- the constraint only
> constrains 1 column in one table...
>
Doesn't the constraint mean that
for any row in table CUST,there *always* exist some rows in
the table XREF such that satisfies XREF_GROUP='CUST_TYPE'
AND XREF_CD=TYPE_CD ?
If all such rows are deleted from the table XREF,above condition
isn't satisfied any longer. So isn't the constraint for the table XREF
either ?
Regards.
Hiroshi Inoue
Inoue(at)tpf(dot)co(dot)jp
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