Re: Foreign Unique Constraint - Mailing list pgsql-sql

From chester c young
Subject Re: Foreign Unique Constraint
Date
Msg-id 415536.67726.qm@web54310.mail.yahoo.com
Whole thread Raw
In response to Foreign Unique Constraint  ("Jon Horsman" <horshaq@gmail.com>)
Responses Re: Foreign Unique Constraint  ("Jon Horsman" <horshaq@gmail.com>)
List pgsql-sql
> 
> create table table1 (
> id SERIAL PRIMARY KEY
> extension UNIQUE,
> <other fields>
> )
> 
> create table table2 (
> id SERIAL PRIMARY KEY
> extension UNIQUE,
> <different fields>
> )
> 
> Basically table 1 and table 2 both have the concept of an extension
> that must be unique but the rest of the info in the tables are
> different.  I need to ensure that if i add an entry to table 1 with
> extension 1000 that it will fail if there is already an entry in
> table2 with the same extension.

use a pre-insert triggers - one for each table.  include something like

if exists( select 1 from table2 where extension=new.extension ) then raise exception ...
end if;




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