สอบถามปัญหาเกี่ยวกับการ Update ข้อมูลแบบ Array ลง SQL ครับ

<?php
foreach($_POST["txtChkbox"] as $key=>$value)
{
	if($_POST["txtChkbox"][$key] != "")
	{
		// สร้างตัวแปรเพื่อทำการรับค่าที่ต้องการเข้ามา เพื่อให้การเรียกใช้งานง่ายขึ้น
		$DATA_CHK = $_POST["txtChkbox"][$key];
		$DATA_ORDERS = $_POST["txtOrders"][$key];
		$DATA_ID = $_POST["txtID"][$key];
		
		//ทดลองแสดงค่า
		/*print "ID = ".$DATA_ID."<br>";
		print "ORDER = ".$DATA_ORDERS."<br>";
		print "TEST = ".$DATA_CHK."<br>";
		print "========================== <p>";*/
		
		$serverName = "localhost";
		$userName = "root";
		$userPassword = "1234";
		$dbName = "purchasenewtest";

		$conn = mysqli_connect($serverName,$userName,$userPassword,$dbName);
		mysqli_set_charset($conn, 'utf8');

		$sql = " UPDATE   idr   SET 
				 orders = '".$DATA_ORDERS."' 
				 WHERE id = '".$DATA_ID."' ";	
			
		$query = mysqli_query($conn,$sql);
		
		if($query) {
		echo " <p align=center> Record update success fully </p> ";	
		}
		
	}
}
		
?>

<form action="testo2.php" name="form1" method="post">
<div align="center"><table width="75%" border="1">
<tr>
<th width="10%"> <div align="center">ID R </div></th>
<th width="20%"> <div align="center">รายการ </div></th>
<th width="10%"> <div align="center">User</div></th>
<th width="5%"> <div align="center"><p>Dept</p></div></th>
<th width="3%"> <div align="center"></div></th>
</tr>

<?php
$i=0;
	while($i<$num && $data1 = $result->fetch_assoc())
	{
?>

<tr>
<td><center><?php echo $data1["datesign"];?>-00<?php echo $data1["idr"]; ?></a></center></td>
<input type="hidden" name="txtID[<?php echo $data1["id"];?>]"value="<?php echo $data1["id"];?>">
<td><center><input type="text" name="txtOrders[<?php echo $data1["id"];?>]" id="txtOrders" size='85' 
	value="<?php echo $data1["orders"];?>"></center></td>
<td><center><?php echo $data1["name"];?> <?php echo $data1["surname"];?> </center></td>
<td><center><?php echo $data1["department"];?></center></td>
<td><center><input type="checkbox" name="txtChkbox[<?php echo $data1["id"];?>]" id="txtChkbox" 
  	value="<?php echo $i++; ?>" ></center></td> 
  
<?php
	}
?>

</table>
</div>

<div align="center">
<br></br>
<input type="submit" value="Submit">
<input type=button onClick='window.history.back()' value='Back'>
</div> 
</form>

<input type="hidden" name="txtID[<?php echo $data1["id"];?>]"value="<?php echo $data1["id"];?>">