From: | Jerome Alet <alet(at)librelogiciel(dot)com> |
---|---|
To: | pgsql-sql(at)postgresql(dot)org |
Subject: | not sure about constraints |
Date: | 2005-09-02 13:23:56 |
Message-ID: | 20050902132356.GD10284@mail.librelogiciel.com |
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Thread: | |
Lists: | pgsql-sql |
Hello,
I've got 4 tables :
CREATE TABLE tableA (id SERIAL PRIMARY KEY NOT NULL,
blahA TEXT);
CREATE TABLE tableB (id SERIAL PRIMARY KEY NOT NULL,
blahB TEXT);
CREATE TABLE tableC (id SERIAL PRIMARY KEY NOT NULL,
ida INT4 REFERENCES tableA(id),
idb INT4 REFERENCES tableB(id),
blahC TEXT);
CREATE TABLE tableD
(id SERIAL PRIMARY KEY NOT NULL,
ida INT4,
idb INT4,
blahC TEXT,
CONSTRAINT checkAB FOREIGN KEY (ida, idb) REFERENCES tableC(ida, idb));
Is the definition of tableD sufficient, or should I do it this way
instead :
CREATE TABLE tableD
(id SERIAL PRIMARY KEY NOT NULL,
ida INT4 REFERENCES tableA(id),
idb INT4 REFERENCES tableB(id),
blahD TEXT,
CONSTRAINT checkAB FOREIGN KEY (ida, idb) REFERENCES tableC(ida, idb));
which looks superfluous to me.
???
Thanks in advance
Jerome Alet
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