在ajax中编辑后发出警报

Question

I am implementing a simple insert and edit using ajax however on the edit it is not displaying the alert and while insertion it is telling undefined index despite my field names are as in my database

edit.php

<?php
    $connect=mysqli_connect("localhost","root","") or die('Could not connect: '.mysqli_error()); mysqli_select_db($connect,'elearning') or die ('database not found: '.mysqli_error()); 
    $id = $_POST["pageID"]; 
    $text = $_POST["text"]; 
    $column_name = $_POST["column_name"];
    $sql = "UPDATE page SET ".$column_name."='".$text."' WHERE pageID='".$id."'"; 
    if(mysqli_query($connect, $sql)) { echo 'Data Updated'; } 
?>

page.php

<script>
  $(document).ready(function() {
    function fetch_data() {
      $.ajax({
        url: "select.php",
        method: "POST",
        success: function(data) {
          $('#live_data').html(data);
        }
      });
    }
    fetch_data();
    $(document).on('click', '#btn_add', function() {
      var cid = $('#cid').text();
      var name = $('#name').text();
      var icon = $('#icon').text();
      var src = $('#src').text();
      var hint = $('#hint').text();
      var category = $('#category').text();

      $.ajax({
        url: "insert.php",
        method: "POST",
        data: {
          cid: cid,
          name: name,
          icon: icon,
          src: src,
          hint: hint,
          category: category
        },
        dataType: "text",
        success: function(data) {
          alert(data);
          fetch_data();
        }
      })
    });

    function edit_data(id, text, column_name) {
      $.ajax({
        url: "edit.php",
        method: "POST",
        data: {
          pageID: id,
          text: text,
          column_name: column_name
        },
        dataType: "text",
        success: function(data) {
          alert(data);
        }
      });
    }

    $(document).on('click', '.btn_delete', function() {
      var id = $(this).data("id7");
      if (confirm("Are you sure you want to delete this?")) {
        $.ajax({
          url: "delete.php",
          method: "POST",
          data: {
            pageID: id
          },
          dataType: "text",
          success: function(data) {
            alert(data);
            fetch_data();
          }
        });
      }
    });
  });
</script>

</div>