Randomize Select

Anon

Hello,

I must to randomize one record on my select with out before generate a rand number.

For example:

SELECT * FROM table WHERE id = (rand number in bound acceptable)

Any sugestions are welcome =)

Regards

Anon

So you could use php's rand() function to generate that number right?

Anon

Well,

It´s easy, but before I need:

$con = pg_connect("bla");
$sql = "select count(*) as rNum from table";
$rs = pg_exec($con, $sql);

then I will rand using rNum, but I think there is a "more pratical" way to make it...

Anon

From my experience a logical way to do this is to generate a random number first and then use this as an offset for your select statement, whilst limiting the results to 1.

That rand() function has never worked for me.....as with many others I think?

scott d~

Anon

Here is an example of its use. I use it to generate a 40 character session ID for database administrators and users connecting to a remote backend MySQL database through a web interface.

function generateSID() { 

	//set a random seed using current time
	srand(time()); 

	//set up the pool from which the session ID number will be pulled
	$var = "ABCDEFGHJKLMNPQRTUVWXY1234567890abcdefghijkmnopqrstuvwxyz1234567890"; 

	//begin the first character of session ID number
	$sid .= substr($Pool,(rand()%(strlen($var))),1); 

	//add the 39 other characters of the session ID number
	for($i = 0; $i < 39; $i++) {
		$sid .= substr($var,(rand()%(strlen($var))),1);
	}

	//return the session ID number
	return $sid; 
}

Hope it shows that rand() does work.

Jim

Anon

Oops, sorry, the line:

$sid .= substr($Pool,(rand()%(strlen($var))),1);

should read

$sid .= substr($var,(rand()%(strlen($var))),1);

Jim

Anon

I think you can just do the following sql call:

select whatever where whatever order by rand() limit 1

that should. hope it helps. this thread is pretty old!