Re: can this be done with a check expression? - Mailing list pgsql-sql

From Wayne Cuddy
Subject Re: can this be done with a check expression?
Date
Msg-id 20120803195053.GA16371@slacker.ja10629.home
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In response to Re: can this be done with a check expression?  ("Jonathan S. Katz" <jonathan.katz@excoventures.com>)
Responses Re: can this be done with a check expression?  (Wayne Cuddy <lists-pgsql@useunix.net>)
List pgsql-sql
Thanks for the input.

I don't insert into this table that often so I'll just prevent overlaps
at the application level since I'm running 9.0.X and not really in a
position to upgrade right now.

Thanks again,

Wayne

On Fri, Aug 03, 2012 at 11:50:13AM -0400, Jonathan S. Katz wrote:
> On Aug 2, 2012, at 7:10 PM, Wayne Cuddy wrote:
> 
> > I have a table with 3 columns:
> > 
> > name text
> > start_id integer
> > end_id integer
> > 
> > start_id and end_id are ranges which must not overlap but can have gaps
> > between them. Is it possible to formulate a table check constraint that
> > can verify that either id does not fall within an existing range at
> > insert time? IE prevent overlaps during insert?
> > 
> > Thanks,
> > Wayne
> 
> So this answer will not help you for the here-and-now, but Postgres 9.2 is going to be released in the near future
(thoughthe beta is available) and contains "range types" which have check constraints on them:
 
> 
> http://www.postgresql.org/docs/9.2/static/rangetypes.html#RANGETYPES-CONSTRAINT
> 
> You could formulate a check constraint right now to do the equivalent, albeit it will involve a lot of conditions.
> 
> Jonathan


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