Re: Subselect with no records results in final empty set
От | Sterpu Victor |
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Тема | Re: Subselect with no records results in final empty set |
Дата | |
Msg-id | em1229821c-4842-4814-a4e6-203983f64359@victor-pc обсуждение исходный текст |
Ответ на | Re: Subselect with no records results in final empty set (John R Pierce <pierce@hogranch.com>) |
Список | pgsql-general |
I always have a single row in these selects so the result will have only a row. I must make a single select for a framework that takes as parameter a single select to complete a XML template in a particular situation. ------ Original Message ------ From: "John R Pierce" <pierce@hogranch.com> To: pgsql-general@postgresql.org Sent: 1/29/2015 10:52:25 PM Subject: Re: [GENERAL] Subselect with no records results in final empty set >On 1/29/2015 12:36 PM, Sterpu Victor wrote: >> >>ON(null) never matched. > >NULL is neither true nor false. > >ON somefieldinthejoin IS NULL would be a valid syntax. except, that's >NOT a join condition, a join condition would be ON left_table.something >= right_table.something > >>ON (1=1) > >equivalent to ON TRUE > >but that will cross join everything, so if the left table has N rows >and the right table has M rows, you'll end up with N*M rows in the >result. is that really what you want ?? > > > > >-- john r pierce 37N 122W >somewhere on the middle of the left coast > > > >-- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) >To make changes to your subscription: >http://www.postgresql.org/mailpref/pgsql-general --- This email has been checked for viruses by Avast antivirus software. http://www.avast.com
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