如何编写PHP脚本并在其中使用ORDER BY子句对MySQL表的数据进行排序？

<必修php
   $dbhost = &#39;localhost:3036&#39;;
   $dbuser = &#39;root&#39;;
   $dbpass = &#39;rootpassword&#39;;
   $conn = mysql_connect($dbhost, $dbuser, $dbpass);

   if(! $conn ) {
      die(&#39;Could not connect: &#39; . mysql_error());
   }
   $sql = &#39;SELECT tutorial_id, tutorial_title,
      tutorial_author, submission_date
      FROM tutorials_tbl
      ORDER BY tutorial_author DESC&#39;;

   mysql_select_db(&#39;TUTORIALS&#39;);
   $retval = mysql_query( $sql, $conn );

   if(! $retval ) {
      die(&#39;Could not get data: &#39; . mysql_error());
   }

   while($row = mysql_fetch_array($retval, MYSQL_ASSOC)) {
      echo "Tutorial ID :{$row[&#39;tutorial_id&#39;]} <br> ".
         "Title: {$row[&#39;tutorial_title&#39;]} <br> ".
         "Author: {$row[&#39;tutorial_author&#39;]} <br> ".
         "Submission Date : {$row[&#39;submission_date&#39;]} <br> ".
         "--------------------------------<br>";
      }
   echo "Fetched data successfully";
   mysql_close($conn);
必修>