From: | "Richard Huxton" <dev(at)archonet(dot)com> |
---|---|
To: | "Einar Karttunen" <ekarttun(at)cs(dot)Helsinki(dot)FI> |
Cc: | <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: Foreign keys/unique values and views |
Date: | 2001-03-22 17:12:59 |
Message-ID: | 001f01c0b2f3$6a3db580$1001a8c0@archonet.com |
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Lists: | pgsql-general |
From: "Einar Karttunen" <ekarttun(at)cs(dot)Helsinki(dot)FI>
> On Thu, 22 Mar 2001, Richard Huxton wrote:
> >
> > I have to admit I've never tried referencing a view with a foreign key.
I
> > don't know if it's possible and I have to admit the idea makes me
> > uncomfortable. Can't give a good reason why, but I'd apply constraints
at
> > the table level.
> if one can reference a table with a foreign key it makes possible to
> reference inheritance hierarchies. If I create a view from the parent
> with CREATE VIEW name SELECT * FROM parent; (in v.7.1) it should contain
> the entries from the children as well. Now if I could reference this view
> I could simulate referencing parent and child tables easily.
> What I have in mind is a hierarchy of persons all inheriting from a table
> called person. Different kinds of persons have different attributes but
> all have an id and name. What I want is that other tables could reference
> these persons easily.
Ah - makes sense. I must admit I don't use inheritence/arrays since I never
know what platform I'll end up running on, so I like to keep things to
standard SQL where possible.
Trying the obvious (reference an id field in the parent) fails on execution:
referential integrity violation - key referenced from bar not found in
foo_parent
You also can't reference the id field in the child table.
There's a question on this on the pgsql-sql list (from Johannes Groden -
dated today) but I don't see any replies yet. This sounds like something
Tom/Bruce will need to get involved in.
- Richard Huxton
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