Mini Shell

<?php 
    include '../db/database.php';
    
    $year = $_POST['year'];
    $class_id = $_POST['class_id'];
    $class_name = $_POST['class_name'];
    $lc_id = $_POST['lc_id'];
    $course_id = $_POST['course_id'];
    
    $sql_class = "SELECT class_name FROM class_room WHERE class_name='$class_name' AND academic_year='$year' AND lc_id='$lc_id' AND course='$course_id' ";
    $result_class = mysqli_query($link2, $sql_class);
    $is_class = mysqli_num_rows($result_class);
    if ($is_class == 1) {
        header('Content-Type: application/json');
        $errors = "ห้องเรียนนี้มีอยู่แล้วในระบบ" . mysqli_error($link);
        echo json_encode(array('status' => 'danger','message' => $errors));
        exit;
    }
    
     $sql = "UPDATE `class_room` SET  `academic_year`='$year',`class_name`='$class_name',`lc_id`='$lc_id',`course`='$course_id'  WHERE (`class_id`='$class_id')";
     $result = mysqli_query($link2, $sql);
     
   if ($result) {
         header('Content-Type: application/json');
         echo json_encode(array('status' => 'success','message' => 'แก้ไขข้อมูลเรียบร้อยแล้ว'));     
    } else {
        header('Content-Type: application/json');
        $errors = "เกิดข้อผิดผลาดไม่สามารถบันทึกข้อมูลได้" . mysqli_error($link);
        echo json_encode(array('status' => 'danger','message' => $errors));
    }