Re: multi-table unique index

On Monday 23 Jun 2003 2:58 pm, Markus Bertheau wrote:
> -- Suppose I have several types of foos
>
> create table foo_types (
>     foo_type_id serial primary key,
>     foo_name text not null
> );
>
> -- And the foos itself:
>
> create table foo (
>     foo_id serial primary key,
>     foo_type_id int not null references foo_types,
>     foo_general_data1 text
> );
>
> -- 1st special foo:
>
> create table foo_1 (
>     foo_1_id serial primary key,
>     foo_id int not null references foo,
>     foo_1_data1 int,
>     foo_1_data2 text
> );

An alternative to Markus' ideas in the other thread - store the type in
foo/foo_1, then have a foreign key over both. The irritating thing is that
you're duplicating the type info unnecessarily.

CREATE TABLE foo (foo_id   serial unique,foo_type_id int not null references foo_types,...PRIMARY KEY
(foo_id,foo_type_id)
);

CREATE TABLE foo_1 (extra_foo   int4 not null,extra_type int4 not nullextra1    text,PRIMARY KEY (extra_foo,
extra_type)CONSTRAINTlink_to_foo FOREIGN KEY (extra_foo,extra_type) REFERENCES foo_core  
(foo_id, foo_type_id)
);


--  Richard Huxton