Comments on: Solutions to the ORDER BY RAND() problem. http://www.koopman.me/2009/01/solutions-to-the-order-by-rand-problem/ Dave Koopman's Blog Wed, 08 Feb 2012 22:35:41 +0000 hourly 1 http://wordpress.org/?v=3.3 By: DaveK http://www.koopman.me/2009/01/solutions-to-the-order-by-rand-problem/comment-page-1/#comment-43 DaveK Sun, 19 Apr 2009 05:52:32 +0000 http://www.koopman.me/?p=1361#comment-43 Only works when you want one result. Back to the drawing board if you want more than one. Might be better to run in a loop, pseudo code: $max = SELECT MAX(`id`) FROM `tbl`) $results = array() $numToGet = 100 while (count($results) < $numToGet) SELECT * FROM `tbl` AS `l1` JOIN (SELECT (RAND() * $max) AS `id`) AS `l2` WHERE `l1`.`id` >= `l2`.`id` AND l1.id NOT IN ($results) ORDER BY `l1`.`id` ASC LIMIT 1 INTO $results[] end while Only works when you want one result. Back to the drawing board if you want more than one. Might be better to run in a loop, pseudo code:

$max = SELECT MAX(`id`) FROM `tbl`)
$results = array()
$numToGet = 100
while (count($results) < $numToGet)

SELECT *
FROM `tbl` AS `l1`
JOIN
(SELECT (RAND() * $max) AS `id`) AS `l2`
WHERE
`l1`.`id` >= `l2`.`id`
AND l1.id NOT IN ($results)
ORDER BY
`l1`.`id` ASC
LIMIT 1
INTO $results[]

end while

]]> By: Dan http://www.koopman.me/2009/01/solutions-to-the-order-by-rand-problem/comment-page-1/#comment-35 Dan Fri, 09 Jan 2009 17:24:40 +0000 http://www.koopman.me/?p=1361#comment-35 Wow! What a great solution to the order by rand problem! I always wondered how to get around order by rand issues, the performance of order by rand is just horrible! This is a fast and speedy work around! Wow! What a great solution to the order by rand problem! I always wondered how to get around order by rand issues, the performance of order by rand is just horrible! This is a fast and speedy work around!

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