I tried this and I get a syntax error.
I think it is because it puts the limit statement before the WHERE clause.
However, I have got it to work, by changing
$rswhatever = mysql_query($query_rswhatever, $database) or die(mysql_error());
to
$rswhatever = mysql_query($query_rswhatever." LIMIT 500", $database) or die(mysql_error());
Thanks for your help