From: Graham Anderson (grahamasiren.cc)
Date: Mon Oct 03 2005 - 12:53:39 CDT

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In the below query, the results first row is usually the same 3-4
tracks out of 30.

so should I use PHP to generate a random seed, $r, and pass that to the
query ?
ORDER BY RAND($r)
or, can it be done just with mysql

many thanks
g
On Oct 3, 2005, at 10:15 AM, Michael Stassen wrote:

> Graham Anderson wrote:
>> is there a way to make ORDER BY RAND() a bit more spontaneous ?
>> I am using it in a php statement:
>> $sql = "SELECT media.id,
>> artist.name as artist,
>> artist.spanish as bio,
>> artist.purchaseLink,
>> artist.picture,
>> media.spanish as trackName,
>> media.path,
>> media.quality,
>> mediaType.id as mediaType
>> FROM artist, media, playlistItems, mediaType
>> WHERE playlistItems.playlist_id = $myID
>> AND playlistItems.media_id = media.id
>> AND media.artist_id = artist.id
>> AND media.mediaType_id = mediaType.id
>> ORDER BY RAND() LIMIT 0, 30";
>> the result seems to be pretty predictable ....
>> is there a way to improve RAND() or is there something better ?
>> Should I be using php to randomize the found set instead ?
>> many thanks
>> g
>
> I don't think anyone can answer this, as is. RAND() is meant to
> produce a pseudo-random sequence that is not truly random in the
> mathematical sense, but which is usually good enough for what you
> appear to be doing. The manual
> <http://dev.mysql.com/doc/mysql/en/mathematical-functions.html> puts
> it this way, "RAND() is not meant to be a perfect random generator,
> but instead a fast way to generate ad hoc random numbers that is
> portable between platforms for the same MySQL version."
>
> What is your standard for randomness? What do you mean by "the result
> seems to be pretty predictable"? Put another way, what are you
> expecting, and what are you getting?
>
> Michael
>

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