Re: Use of reference table ('look-up-table') and FK constraint

Charles,

CREATE TABLE phone_types (
type VARCHAR(10) NOT NULL PRIMARY KEY
);

INSERT INTO phone_types
VALUE ( 'Work' );
INSERT INTO phone_types
VALUE ( 'Home' );
etc ...

CREATE TABLE phone (
phone_id Identifier_type IDENTITY,
phone_number varchar(20) NOT NULL,
community_id numeric(12) NOT NULL,
type varchar(10) NULL REFERENCES phone_types(type) ON
DELETE SET NULL
);

Simple, neh? And it lets you add new types, at any time, without re-building
the table. IMHO, the guy who built the database you're converting was
either a total hack or working around some serious platform shortcomings.

BTW, are you sure you want phone.type to be NULLable? Were it me, I would
make it required, in which case the declaration would be:

type varchar(10) NOT NULL REFERENCES
phone_types(type)

--
-Josh Berkus
Aglio Database Solutions
San Francisco