Re: Efficient way to count rows when using GROUP BY

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



El Dom 26 Jun 2005 07:39, Ross Honniball escribió:
> Hi All,
> 
> I use 
> 
> SELECT COUNT(*) FROM whatever WHERE whatever
> 
> to determine how many rows a particular query will return (then use this 
count to assist with pagination).
> 
> The problem is that this does not work if the query contains a GROUP BY 
statement as, of course,
> the query will return many rows each with a count by each grouping.
> 
> Does anyone know an efficient way to determine the number of ROWS a query 
with a GROUP BY
> statement will return (without just executing the entire query with no LIMIT 
statement)?

You are not stating which database you are working with, but I would do this 
(don't know if it's efficient, but it'll work):

SELECT sum(count) FROM 
	(SELECT COUNT(*) AS count FROM whatever WHERE whatever) t1;

Hope it helps.

-- 
select 'mmarques' || '@' || 'unl.edu.ar' AS email;
---------------------------------------------------------
Martín Marqués          |   Programador, DBA
Centro de Telemática	|     Administrador
               Universidad Nacional
                    del Litoral
---------------------------------------------------------

-- 
PHP Database Mailing List (http://www.php.net/)
To unsubscribe, visit: http://www.php.net/unsub.php



[Index of Archives]     [PHP Home]     [PHP Users]     [Postgresql Discussion]     [Kernel Newbies]     [Postgresql]     [Yosemite News]

  Powered by Linux