Issue with updating database from checkboxes in table

[Abundances]

if (mysqli_connect_errno())
  {
  echo "Failed to connect to MySQL: " . mysqli_connect_error();
  }

$result = mysqli_query($con,"SELECT * FROM Request");

echo "<table border='1'>

<tr>
<th>First Name</th>
<th>Last Name</th>
<th>Prayer Request</th>
<th>Deactivate Request</th>
</tr>";

while($row = mysqli_fetch_array($result))
  {
  echo "<tr>";
  echo "<td>" . $row['Reg_F_Name'] . "</td>";
  echo "<td>" . $row['Reg_L_Name'] . "</td>";
  echo "<td>" . $row['Reg_Request'] . "</td>";
  echo "<td><input name=\"checkbox[]\" type=\"checkbox\" id=\"checkbox[]\" value=\"".$rows['Reg_ID']. "\" /></td>";  
  echo "</tr>";
  }
echo "</table>";

echo 
"<form action='' method='post'> 
<input type='submit' name='use_button' value='Update' /> 
</form>"; 

if(isset($_POST['use_button'])) 
{ 
    echo "Updated"; 
$update_id = $_POST['checkbox']; 
foreach($update_id as $value){
   $sql = "Update Request  set Reg_Status=0 WHERE Reg_ID='".$value."'";
   $result = mysql_query($sql);
}
	
}

mysqli_close($con);

?>

the database is not updated when i click update. 

[QuickOldCar]

You are mixing mysqli_ and mysql_ functions

 

$result = mysql_query($sql);

[Abundances]

What changes do i need to make to have it update the records that have been selected with the check boxes 

[QuickOldCar]

$con->query($sql);