Re: REFERENCES constraint

Cedar Cox writes:

> CREATE TABLE obj_weights (
> object_id int4 REFERENCES ( apple_objects(id) OR banana_objects(id) )
> weight float4,
> )

The way I would work this out is like this:

CREATE TABLE fruit_objects (
object_id serial PRIMARY KEY,
fruit_type text CHECK (fruit_type IN ('apple', 'banana')),
weight float4,
... other common fruit properties ...
);

CREATE TABLE apple_objects (
object_id integer REFERENCES fruit_objects,
color text,
... more apple properties ...
);

CREATE TABLE banana_objects (
object_id integer REFERENCES fruit_objects,
curvature real,
... other banana properties ...
);

--
Peter Eisentraut peter_e(at)gmx(dot)net http://funkturm.homeip.net/~peter