php - counter ID number instead of random ID number? -

good day, have problem , dont know how counting id number instead of random numbers, please me. thank you. codes working on random id, want in counting number id. thanks

<?php      $hostname_conn = "localhost";      $database_conn = "user_id";      $username_conn = "root";      $password_conn = "";       $conn = mysql_pconnect($hostname_conn, $username_conn,   $password_conn) or trigger_error(mysql_error(),e_user_error);      mysql_select_db($database_conn,$conn);     // run endless loop                  while(1) {                   $randomnumber = mt_rand(10, 100);// generate unique random number                     $query = "select * tblrand the_number='".mysql_real_escape_string ($randomnumber)."'";  // check if exists in database         $res =mysql_query($query,$conn);             $rowcount = mysql_num_rows($res);      $id=$randomnumber;       // if not found in db (it unique), insert unique number data_base , break out of loop      if($rowcount < 1) {      $con = mysql_connect ("localhost","root");            mysql_select_db("user_id", $con);             $sql = "insert tblrand(the_number) values('".$randomnumber."')";            mysql_query ($sql,$con);              mysql_close ($con);      break;      }     }    echo "it-form" .$id;     ?>