I am using PostgreSQL 7.1.1 on a Debian GNU/Linux 3.0 (testing)
system.
In a table definition I used a REFERENCES constraint to a table that
is inherited, thinking that this would ensure that a value for that
column occurred in the table that I named or any of its daughter
tables. I was wrong. Apparently the constraint checks only the
table and not any daughter tables.
If I expressed this in terms of SELECT the distinction would be like
that between 'table' and 'table*' (pre-7.1) or between 'ONLY table'
and 'table' (7.1 and later).
Some details on the application may help. This is a bibliographic
database storing information on books, journal articles, proceedings
articles, book reviews, etc. We refer to any of these as "titles".
Keywords or phrases are stored in the phrase table. Phrases and
titles are related through the keywords table.
Some of the table definitions are:
-- All publications must be listed in the title table.
CREATE TABLE title ( -- a virtual table - do not insert into this
idT SERIAL PRIMARY KEY,
type CHAR(1) CHECK(upper(type) IN ('B', 'E', 'J', 'P', 'R')),
title TEXT NOT NULL
);
-- Information on a journal article is in the article table
CREATE TABLE article (
idE INTEGER REFERENCES jour_vol ON UPDATE CASCADE,
bpg VARCHAR(5) ,
epg VARCHAR(5) ,
PRIMARY KEY (idT)
) INHERITS (title);
-- Book_cont describes the contents of a book
CREATE TABLE book_cont (
idE INTEGER NOT NULL REFERENCES book,
PRIMARY KEY (idT)
) INHERITS (title);
...
-- Keywords or phrases must be listed in the phrase table
CREATE SEQUENCE idpseq; -- stores the default idp value
CREATE TABLE phrase (
idP INT2 PRIMARY KEY DEFAULT nextval('idpseq'),
phrase VARCHAR(80) NOT NULL UNIQUE
);
-- A keyword or phrase is related to a title through the keywords table
CREATE TABLE keywords (
idK SERIAL PRIMARY KEY,
idT INTEGER NOT NULL REFERENCES title ON UPDATE CASCADE,
idP INT2 NOT NULL REFERENCES phrase ON UPDATE CASCADE,
kseq INT2 NOT NULL default 0 CHECK(kseq >= 0)
);
As one of the comments indicates, the title table is a virtual (or
abstract) table. It exists only to characterize the common
characteristics of all titles.
Are there any suggestions on how I can achieve what I want to do? We
are at the design stage right now and I can change the design if
needed.