不应该准备好的报表要快得多吗？

Question

$s = explode (" ", microtime());
$s = $s[0]+$s[1];
$con = mysqli_connect ('localhost', 'test', 'pass', 'db') or die('Err');

for ($i=0; $i<1000; $i++) {

  $stmt = $con -> prepare( " SELECT MAX(id) AS max_id , MIN(id) AS min_id FROM tb ");
  $stmt -> execute();
  $stmt->bind_result($M,$m);
  $stmt->free_result();
  $rand = mt_rand( $m , $M ).'<br/>';

  $res = $con -> prepare( " SELECT * FROM tb WHERE id >= ? LIMIT 0,1 ");
  $res -> bind_param("s", $rand);
  $res -> execute();
  $res->free_result();
}

$e = explode (" ", microtime());
$e = $e[0]+$e[1];
echo  number_format($e-$s, 4, '.', '');

// and:

$link = mysql_connect ("localhost", "test", "pass") or die ();
mysql_select_db ("db") or die ("Unable to select database".mysql_error());

for ($i=0; $i<1000; $i++) {
  $range_result = mysql_query( " SELECT MAX(`id`) AS max_id , MIN(`id`) AS min_id FROM tb ");
  $range_row = mysql_fetch_object( $range_result ); 
  $random = mt_rand( $range_row->min_id , $range_row->max_id );
  $result = mysql_query( " SELECT * FROM tb WHERE id >= $random LIMIT 0,1 ");
}

defenitly prepared statements are much more safer but also every where it says that they are much faster BUT in my test on the above code I have: - 2.45 sec for prepared statements - 5.05 sec for the secon example

What do you think I'm doing wrong? Should I use the second solution or I should try to optimize the prep stmt?

Answer 1

What you are doing wrong is that you are preparing the statement a thousand times and only run each prepared statement once. You should prepare it once, and run it a thousand times.