check if value exsists in database

[rex9990]

hi there,
ive got a page that shows up listings and it gets the id from the database and displays the information. But the problem is that i only want it to be able to get the info from the right database ids, but if you put in a random number like 8123217512 at the top it still displays the page but with no info cuz it doesnt exsist. So what im wondering is how could i check the data first before it displays and go back to homepage if there is no such id??

Here is the first few lines of the page

<?
if(empty($_GET[id]))
{
	header("location:index.php");
	exit();
}
?>

Thanks Steve

[Zyppora]

If you try to select on an ID that doesn’t exist in the database, the result set won’t have any records in it. mysql_num_rows() ftw