First of all, I don't wanna let the query run to the end and after that, count the number of records. as I mentioned, some tables are huge and takes a long time to run COUNT(*) query for all records.
About LIMIT, it doesn't effect on COUNT query. but for the second query ( retreiving a field ) I can use it and as you mentioned, I use LIMIT v1,v2. this part of query that I tried to use COUNT is before retreiving the all fields of the last page. it's just checking for the number of records, to find the number of pages and show the last page. about why I am not using auto_number or other indexes, because the table and conditions are variable and on run-time. ----- Original Message ----- From: "Viorel Dragomir" <[EMAIL PROTECTED]> To: "Mojtaba Faridzad" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Tuesday, July 22, 2003 9:50 AM Subject: Re: how to limit COUNT(*) > ----- Original Message ----- > From: "Mojtaba Faridzad" <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Sent: Tuesday, July 22, 2003 4:40 PM > Subject: Re: how to limit COUNT(*) > > > > for example: > > > > SELECT COUNT(*) as numfound FROM mytable WHERE mycondition; > > > > in this query, mytable and mycondition are variable and on run time, they > > are changed. I use this query to jump to the last page of a grid form. > > sometimes the query may have more than million records and I want to give > a > > warning to the user to specify a condition to limit the number of records. > I > > would like to count the records upto 10000 (for example) and if the > records > > are more than this, stop counting and ask user to change the condition. to > > solve this problem I did something like this: > > > > SELECT one_field FROM mytable WHERE mycondition LIMIT 10001; > > > > if the number of records of this query is equal to 10001, then I show the > > warning message. but this query is not as fast of COUNT query. is there > any > > way to limit the first query? > > > > I dunno if I understood your problem. But if you want to *limit the count()* > try to put a condition after fetching the result. > if( count_result > MAX_NO) then count_result = MAX_NO; > > If you want to paginate your result try use LIMIT v1, v2 [look in manual for > more information about SELECT & LIMIT] > > If you just want to view the last info rows try to order desc over an > auto_increment field. > > good luck > > > thanks > > > > ----- Original Message ----- > > From: "gerald_clark" <[EMAIL PROTECTED]> > > To: "Mojtaba Faridzad" <[EMAIL PROTECTED]> > > Cc: <[EMAIL PROTECTED]> > > Sent: Tuesday, July 22, 2003 9:15 AM > > Subject: Re: how to limit COUNT(*) > > > > > > > Perhaps you could post some examples of what you have tried. > > > I don't understand what you are asking. > > > > > > Mojtaba Faridzad wrote: > > > > > > >Hi, > > > > > > > >I guess there is no way to limit COUNT(*). Is that right? We cannot use > > the > > > >result of COUNT in WHERE condition or LIMIT doesn't help. In this case > so > > > >far I have retrieved a field and used LIMIT. Is there a better way to > > > >control it? > > > > > > > >Thanks > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > MySQL General Mailing List > > > For list archives: http://lists.mysql.com/mysql > > > To unsubscribe: > > http://lists.mysql.com/[EMAIL PROTECTED] > > > > > > > > > -- > > MySQL General Mailing List > > For list archives: http://lists.mysql.com/mysql > > To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED] > > > > -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
