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Home -> Community -> Mailing Lists -> Oracle-L -> Re: [Q] what difference between count(0), count(1) and
Does count(0) , 0 mean first column and 1 mean second column?
Thanks.
>From: "Arn Klammer" <Arn.Klammer_at_austrac.gov.au>
>Reply-To: ORACLE-L_at_fatcity.com
>To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
>Subject: Re: [Q] what difference between count(0), count(1) and
>Date: Wed, 24 Oct 2001 18:40:18 -0800
>
>As I understand it, count(*) counts all rows. Anything other than "*" is
>treated as an expression and it returns the number of rows where that
>expression evaluates to not null. So what Deepak said below about
>count(col1) giving the count of non-null instances of col1 is correct.
>That also means that count(0), count(1), etc should behave the same as
>count(*), as 0, 1, etc are not null.
>
>Now, is count(*) less efficient in execution than count(1)? I've been
>asked this before, and I don't know. I would've thought count(*) and
>count(1) would be the same, execution-wise. Is this correct?
>
>-a
>
> >>> mccdba_at_hotmail.com 25/10/2001 11:30:17 >>>
>This message has been scanned by MAILSweeper.
>************************************************************
>
>Thank you for answer. How about count(0)?
>
>
> >From: Deepak Thapliyal <deepakthapliyal_at_yahoo.com>
> >Reply-To: ORACLE-L_at_fatcity.com
> >To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
> >Subject: Re: [Q] what difference between count(0), count(1) and count(*)
> >Date: Wed, 24 Oct 2001 11:41:11 -0800
> >
> >i think count(*) gives count of all columns .. where
> >as count(col1) gives count for col1 ignoring nulls in
> >col1
> >
> >Deepak
> >--- aaa aaa <mccdba_at_hotmail.com> wrote:
> > > Can anyone tell me what is difference between :
> > >
> > > select count(*) ... from ..
> > >
> > > select count(0) ...
> > >
> > > select coun (1) ...
> > > select count(2) ...
> > >
> > >
> > > Thanks.
> > >
> > >
> > >
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>Author: dist cash
> INET: mccdba_at_hotmail.com
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>Author: Arn Klammer
> INET: Arn.Klammer_at_austrac.gov.au
>
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-- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: dist cash INET: mccdba_at_hotmail.com Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).Received on Thu Oct 25 2001 - 08:08:53 CDT
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