Hi Tarlika, I think easy solution could be:
create baseTable with just one column as PK TableA inhertis baseTable, it will have inherited Column + additianl tables for TableA TableB inherits baseTable, it will aslo have inherited Column + additianl tables for TableB Insert in any table TableA or TableB will automatically insert row in baseTable what will fail if value already exist... Kind Regards, Misa 2011/6/20 Tarlika Elisabeth Schmitz <postgres...@numerixtechnology.de> > 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 > > -- > Sent via pgsql-general mailing list (pgsql-general@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-general >
