Bug on complex join

Hi!

I am continuing playing with the query (I reduced it to):
SELECT sh.distr_id , d.distr_id
FROM central cn, shops sh, districts d
WHERE cn.shop_id = sh.shop_id

and got 27963 rows. I filtered it out (with awk:) where $1 == $2 (1st
column is equal to second) and got 3104 rows.

But the query
SELECT d.*
FROM central cn, shops sh, districts d
WHERE cn.shop_id = sh.shop_id AND sh.distr_id = d.distr_id

returned 0 rows.

Where is the bug?

Oleg.
----
Oleg Broytmann http://members.xoom.com/phd2/ phd2(at)earthling(dot)net
Programmers don't die, they just GOSUB without RETURN.