From: Tom Lane <tgl@sss.pgh.pa.us>
To: Mario Splivalo <mario.splivalo@megafon.hr>
Cc: pgsql-sql@postgresql.org
Subject: Re: CHECK constraint on multiple tables
Date: Mon, 14 Sep 2009 10:18:15 -0400
Message-ID: <15921.1252937895@sss.pgh.pa.us> (raw)
In-Reply-To: <4AAE43F8.4000107@megafon.hr>
References: <4AAE43F8.4000107@megafon.hr>
Mario Splivalo <mario.splivalo@megafon.hr> writes:
> I have two tables, tableA and tableB:
> CREATE TABLE tableA (idA integer primary key, email character varying
> unique);
> CREATE TABLE tableB (idB integer primary key, email character varying
> unique);
> Now, I want to create check constraint in both tables that would
> disallow records to either table where email is 'mentioned' in other table.
Have you considered refactoring so there's only one table?
Cross-table constraints are a really bad idea unless you can express
them as foreign keys. There's a lot of "secret sauce" in the FK
mechanism that isn't available to user-written constraints.
regards, tom lane
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To: pgsql-sql@postgresql.org
Cc: tgl@sss.pgh.pa.us, mario.splivalo@megafon.hr
Subject: Re: CHECK constraint on multiple tables
In-Reply-To: <15921.1252937895@sss.pgh.pa.us>
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