From: | Tarlika Elisabeth Schmitz <postgresql4(at)numerixtechnology(dot)de> |
---|---|
To: | pgsql-general(at)postgresql(dot)org |
Subject: | unique across two tables |
Date: | 2011-06-20 15:03:07 |
Message-ID: | 20110620160307.683ab611@dick.coachhouse |
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Thread: | |
Lists: | pgsql-general |
I have two tables, town and townalias, the latter containing alternative
town names.
I would like to ensure that a town name is unique per
country-region across the two tables.
Can I do this with a constraint ot do I need to implement the logic via
trigger?
=========
PostgreSQl 8.4
CREATE TABLE town
(
country_fk character varying(3) NOT NULL,
region_fk character varying(3) NOT NULL,
id serial NOT NULL,
"name" character varying(50) NOT NULL
)
CREATE TABLE townalias
(
country_fk character varying(3) NOT NULL,
region_fk character varying(3) NOT NULL,
town_fk integer NOT NULL,
id serial NOT NULL,
"name" character varying(50) NOT NULL,
CONSTRAINT town_townalias_fk FOREIGN KEY (country_fk, region_fk,
town_fk) REFERENCES town (country_fk, region_fk, id)
)
--
Best Regards,
Tarlika Elisabeth Schmitz
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