資料都已經撈出來至陣列中了

請問有什麼方法可以比較當 'work_order_no','created_at','DDTEXT',{'position'}這四個欄位值相同時只顯示一筆資料就好，並計算有多少筆資料是相同的?

程式碼 :

$sql = "SELECT a.work_order_no,a.product_no,b.ARBPL2,substring(c.created_at,1,10) as created_at ,c.ng_no,d.DDTEXT,c.data,c.ng_count,c.machine_work_id 
		FROM machine_work a,machine b,machine_work_detail c,ngreason d
		WHERE  a.id = c.machine_work_id and a.machine_no = b.ARBPL and c.ng_no = d.ZZDEFECT and c.ng_count > 0 and c.data !='' 
		" ;

$sql.="ORDER BY `a`.`work_order_no` ASC,`c`.`ng_no` ASC";
//echo $sql;

$result = $pdo->query($sql);
		
while($row = $result->fetch(PDO::FETCH_ASSOC))
{
	$obj = json_decode($row['data'],false);
	
	print_r($row);
	echo "<br>";

	echo "<tr>";
	echo "<td>".$row['work_order_no']."</td>";
	echo "<td>".$row['product_no']."</td>";
	echo "<td>".$row['ARBPL2']."</td>";
	echo "<td>".$row['created_at']."</td>";
	echo "<td>".$row['DDTEXT']."</td>";
	echo "<td>".$obj->{'position'}."</td>";
	echo "<td>".$row['ng_count']."</td>";
	echo "</tr>";
	//echo "<br>";

}

?>

我的$sql是從多個table撈進來的整理，不太適合用distinct
有沒有可以往array的方向去解?