รบกวนเรื่อง นับจำนวน ชื่อใน colum ถ้ามี ID ซ้ำกันให้นับเป็ฯ 1 ครับ

<?
include "connect.php";
$tb="db_mc";
$sql="select * from $tb Group by mc_id";
$result = mysql_query($sql);
While($row= mysql_fetch_array($result)){
$mc_id = $row["mc_id"];
$mc_name = $row["mc_name"];
$a++;
	
	$tb2="db_mc";
	$sql_search="select DISTINCT id from $tb2 where mc_id='$mc_id'";
	$sql_select=mysql_query($sql_search);
	$num=mysql_num_rows($sql_select);

  ?>

$sql="select * from $tb Group by mc_id";

$tb2="db_mc";
	$sql_search="select DISTINCT id from $tb2 where mc_id='$mc_id'";
	$sql_select=mysql_query($sql_search);
	$num=mysql_num_rows($sql_select);