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Re: A strange problem

From: Douglas McNaught <doug(at)mcnaught(dot)org>
To: Tang Tim Hei <timheit(at)netvigator(dot)com>
Cc: <pgsql-general(at)postgresql(dot)org>
Subject: Re: A strange problem
Date: 2005-08-27 15:24:34
Message-ID: m24q9bo11p.fsf@Douglas-McNaughts-Powerbook.local (view raw, whole thread or download thread mbox)
Lists: pgsql-general
Tang Tim Hei <timheit(at)netvigator(dot)com> writes:

> Hi,
>   I'm new to postgresql. Anytime I type the following command to the database to run, it give me no result record if table 'country' is empty but can get result if 'country' is not empty. Is this so strange?
>   select A.* from test.currency A, B where A.curr_cd='USD'

You're doing an unconstrained join on "currency" and "country", and if
one of those two tables is empty the result will be empty.


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