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 >>> [EMAIL PROTECTED] 25/10/2001 11:30:17 >>> This message has been scanned by MAILSweeper. ************************************************************ Thank you for answer. How about count(0)? >From: Deepak Thapliyal <[EMAIL PROTECTED]> >Reply-To: [EMAIL PROTECTED] >To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]> >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 <[EMAIL PROTECTED]> wrote: > > Can anyone tell me what is difference between : > > > > select count(*) ... from .. > > > > select count(0) ... > > > > select coun (1) ... > > select count(2) ... > > > > > > Thanks. > > > > > > >_________________________________________________________________ > > Get your FREE download of MSN Explorer at > > http://explorer.msn.com/intl.asp > > > > -- > > Please see the official ORACLE-L FAQ: > > http://www.orafaq.com > > -- > > Author: aaa aaa > > INET: [EMAIL PROTECTED] > > > > 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: [EMAIL PROTECTED] (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). > > >__________________________________________________ >Do You Yahoo!? >Make a great connection at Yahoo! Personals. >http://personals.yahoo.com >-- >Please see the official ORACLE-L FAQ: http://www.orafaq.com >-- >Author: Deepak Thapliyal > INET: [EMAIL PROTECTED] > >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: [EMAIL PROTECTED] (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). _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp - - Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: dist cash INET: [EMAIL PROTECTED] 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: [EMAIL PROTECTED] (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). ********************************************************************** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This footnote also confirms that this email message has been swept by MIMEsweeper for the presence of computer viruses. www.mimesweeper.com ********************************************************************** -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Arn Klammer INET: [EMAIL PROTECTED] 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: [EMAIL PROTECTED] (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).
