Re: Column as result of subtraction of two other columns?
От | Mark Cave-Ayland |
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Тема | Re: Column as result of subtraction of two other columns? |
Дата | |
Msg-id | 8F4A22E017460A458DB7BBAB65CA6AE5026612@openmanage обсуждение исходный текст |
Ответ на | Column as result of subtraction of two other columns? ("Mark Cave-Ayland" <m.cave-ayland@webbased.co.uk>) |
Список | pgsql-general |
> -----Original Message----- > From: John Sidney-Woollett [mailto:johnsw@wardbrook.com] > Sent: 16 July 2004 16:22 > To: Bruno Wolff III > Cc: Mark Cave-Ayland; pgsql-general@postgresql.org > Subject: Re: [GENERAL] Column as result of subtraction of two > other columns? > > > Try > > select a, b, (b - a) as diff from ( > select 1 as a, 2 as b > ) as tmp; > > John Sidney-Woollett Hi John, Brilliant - thanks for this! The reason I would like to do it this way is because in my real database, both a and b are horribly complex with 6 or more joins, and it seems a waste for the database to calculate both results again just to give the difference. I'll give this a go on Monday and shout if I still can't get it to work. Many thanks, Mark. --- Mark Cave-Ayland Webbased Ltd. Tamar Science Park Derriford Plymouth PL6 8BX England Tel: +44 (0)1752 764445 Fax: +44 (0)1752 764446 This email and any attachments are confidential to the intended recipient and may also be privileged. If you are not the intended recipient please delete it from your system and notify the sender. You should not copy it or use it for any purpose nor disclose or distribute its contents to any other person.
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