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Re: special integrity constraints

From: Achilleus Mantzios <achill(at)matrix(dot)gatewaynet(dot)com>
To: Erik Thiele <erik(at)thiele-hydraulik(dot)de>
Cc: pgsql-sql(at)postgresql(dot)org
Subject: Re: special integrity constraints
Date: 2004-03-22 10:13:29
Message-ID: Pine.LNX.4.44.0403221212500.31407-100000@matrix.gatewaynet.com (view raw or flat)
Thread:
Lists: pgsql-docspgsql-sql
O kyrios Erik Thiele egrapse stis Mar 22, 2004 :

Did you check out the DEFERRABLE option on the constraint?

> hi,
> 
> i have two tables
> 
> create table a (x integer);
> create table b (y real);
> 
> i have the special constraint that the sum of the number of rows in
> table a plus the number of rows in table b must be even.
> 
> so there is a posibility of adding one element to a and one element to
> b, and again the constraint is met.
> 
> but this of course does not work, since between adding the element to a
> and adding the element to b, the constraint is not met.
> 
> so i cannot use a trigger.
> 
> what i need is the execution of a check procedure at commit time. is
> that somehow possible?
> 
> my database has much more tables than just a and b, and most time the other
> tables are modified and not a or b, so it would be nice to execute the
> constraint checking procedure only if a or b was modified.
> 
> yes :) this question i asked in my former mail too, but I think it
> looked like there was a workaround and my problem was wrong. so i
> created this new kind of problem here to make things clearer.
> 
> 
> cu
> Erik
> 
> 
> 

-- 
-Achilleus


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