I am trying to select the most common 100 names from a table then display the list showing the names and count. I want the user to be able to re-sort the list alphabetically rather than based on count.

I thought the following code would do it. It works for the default sort by count but fails on the sort alphabetically. The line "$count = mysql_num_rows($table);" gives an error: mysql_num_rows() expects parameter 1 to be resource, boolean given. Any help would be greatly appreciated.

// Get most popular surnames
         echo '<h2>Most Common Surnames</h2>';
         if ($sort == "") {  // default sort by count
             echo '<a href="http://mysite/names.php?id='.$id.'&sort=name">Sort by name</a><br>';
             $query = "SELECT family_name, COUNT(*) as count FROM namefile 
                        WHERE record_key = $id
                        GROUP BY family_name
                    ORDER BY count DESC LIMIT 100";
     }
     else {  // sort alphabetically
         echo '<a href="http://mysite/names.php?id='.$id.'">Sort by count</a><br>';
         $query = "SELECT * FROM (
                    SELECT family_name, COUNT(*) as count FROM namefile 
                    WHERE record_key = $id
                    GROUP BY family_name
                    ORDER BY count DESC LIMIT 100)
                    AS alpha ORDER BY family_name";
     }
     $table = mysql_query($query);
     $count = mysql_num_rows($table);
 $tot = 0;
 $i = 0;
 echo '<table><tr>';
 while ($tot < $count2) {
     $rec2 = mysql_fetch_array($table2);
     echo '<td>'.$rec2[0].'</td><td>'.$rec2[1].'</td><td width="40">&nbsp;</td><td>';
       if ($i++ == 6) {
         echo '</tr><tr>';
         $i = 0;
       }
     $tot++;
 }
 echo '</tr></table><br>';

UPDATE: I needed to add "AS alpha" to give the outer select a unique name. (alpha is just a random name I made up.) It now works perfectly. Code updated for the benefit of any others who need something similar.