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help / color / mirror / Atom feedFrom: Daryl Sayers <daryl@stone.oz.au>
To: postgres@postgres.Berkeley.EDU
Date: Mon, 6 Nov 95 10:41:44 AEST
Message-ID: <9511061041.aa16227@odtdev.stone.oz.au> (raw)
Newsgroups: stone.mlist.postgres
Path: daryl
From: daryl@stone.oz.au (Daryl Sayers)
Subject: Re: Simple retrieve question
Organization: Stone Microsystems, NSW, Australia
Date: Mon, 6 Nov 1995 00:41:37 GMT
Message-ID: <DHLJ9D.CI9@stone.oz.au>
X-Newsreader: NN version 6.5.0 #3
References: <9511031223.aa22499@odtdev.stone.oz.au>
>O.K. call me lame, but I can't figure it out.....
>I have 2 classes, One for Company info and 1 for Contacts.
>For every Contact record there is an id that points to the
>Company it belongs to. My questions how can I retrieve all
>the Companys that do not have a Contact record.
O.K. Here is some more information as the kind souls that answered
me all suggested similar ideas that I had already tried.
retrieve (u.name)
from u in company, v in contact
where u.id != v.id
This doesnt work because it goes through all the Companys and checks against
all Contacts.
example:
Class Company Class Contacts
id Company id Contact
1 AAAA 1 Fred Dag
2 BBBB 1 Joe Bloggs
3 CCCC 3 Pete Smith
The command above will produce a list:
(u.id != v.id)
( 1 != 1 ) Dont Print AAAA
(u.id != v.id)
( 2 != 1 ) **** Print BBBB BBBB
(u.id != v.id)
( 3 != 1 ) **** Print CCCC CCCC
(u.id != v.id)
( 1 != 1 ) Dont Print AAAA
(u.id != v.id)
( 2 != 1 ) **** Print BBBB BBBB
(u.id != v.id)
( 3 != 1 ) **** Print CCCC CCCC
(u.id != v.id)
( 1 != 3 ) **** Print AAAA AAAA
(u.id != v.id)
( 2 != 3 ) **** Print BBBB BBBB
(u.id != v.id)
( 3 != 3 ) Dont Print CCCC
I am using postgres4.2
--
Daryl Sayers Ph: (02) 417 3788
Stone Group Asia Pacific Fax: (02) 417 3741
Unit 20, 380 Eastern Valley Way Email: daryl@stone.oz.au
Roseville, 2069 NSW Australia WWW: http://sydney.DIALix.com/~stone
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