codice:
function getmicrotime(){
   list($usec, $sec) = explode(" ",microtime());
   return ((float)$usec + (float)$sec);
   }

$time_start = getmicrotime();
  
//for ($i=0; $i < 1000; $i++){
//   //do nothing, 1000 times
//   }
$st=mysql_query("SELECT * FROM tabella");


$time_end = getmicrotime();
$time = $time_end - $time_start;

echo "Did nothing in $time seconds";