Re: [SQL] OUTER JOINS

At 16:26 +0300 on 19/04/1999, Dan Janowski wrote:

> Thanks for giving it a stab. Looking at the available
> operators,
> there is no =* or *= ops available. Although I am curious
> where it
> comes from.

To the best of my knowledge, outer joins are not yet supported in
PostgreSQL. As far as I recall, you can achieve the same effect with a
union.

For example, if you have a people table and a pets table, where each
person's pet is joined to the owner by the owner's id colum, you'll
theoretically do something like:

SELECT surname, firstname, pet_name
FROM people, pets
WHERE id *= owner_id
ORDER BY surname, firstname;

So instead, you'll have to do something like:

SELECT surname, firstname, pet_name
FROM people, pets
WHERE id = owner_id
UNION
SELECT surname, firstname, null
FROM people
WHERE not exist (
SELECT 1
FROM pets
WHERE owner_id = id
)
ORDER BY surname, firstname;

Excuse me if I goofed something syntactically, I don't have time to
actually create the tables and test the above. Note, however, that a UNION
removes duplicates.

Herouth

--
Herouth Maoz, Internet developer.
Open University of Israel - Telem project
http://telem.openu.ac.il/~herutma