菜鸟级问题，望高手不吝赐教！

//我根据$id来查询某条记录的详细信息
<?php
  // error_reporting(0);
   $db=mysql_connect("localhost","root");
   mysql_select_db("wuyc",$db);
   if($id)
   {
       $result=mysql_query("Select * from employees where id=$id",$db);
       $myrow=mysql_fetch_array($result);
       echo "<p><table border=1 align=center><caption>id为 $id 的详细情况</caption>";
       echo "<tr bgcolor=#c0c0c0><td>id</td><td>First name</td><td>Last Name</td><td>Address</td><td>Position</td></tr>";
       echo "<tr>";
       printf("<td>%d</td>",$myrow[0]);
       printf("<td>%s</td>",$myrow[1]);
       printf("<td>%s</td>",$myrow[2]);
       printf("<td>%s</td>",$myrow[3]);
       printf("<td>%s</td>",$myrow[4]);
       printf("</tr></table>");
       
   }
   else
   {
     $result=mysql_query("Select * from employees",$db);
     echo "<p><table border=1 align=center><caption>Employees 详细记录</caption>";
     echo "<tr><td>id</td><td>First name</td><td>Last Name</td><td>Address</td><td>Position</td></tr>";
     while($myrow=mysql_fetch_array($result)){
         echo "<tr>";
         printf("<td><a href=\"%s?id=%d\">%d</a></td>",$PATHINFO,$myrow[0],$myrow[0]);
         printf("<td>%s</td>",$myrow[1]);
         printf("<td>%s</td>",$myrow[2]);
         printf("<td>%s</td>",$myrow[3]);
         printf("<td>%s</td>",$myrow[4]);
         printf("</tr>");
     }
     echo "</table>";
   }
 ?>