no errors ....no results i tried - php

Question

i am not getting any result ..tried a lot ...but didnt know what is the problem.
no results after editing...nothing changed ...and is also not showing any error..please help..i need to submit a project.'
Thankyou.
<form action="acat.php" method="post"> <!--Edit cat form-->
<div class ="form-group">
<label for ="title">Edit Category</label>
<?php
if(isset($_GET['edit'])) {
$editid = $_GET['edit'];
if (!$editid) {
echo "CANNOT BE EDITED";
} else {
$query = "SELECT * FROM categories WHERE cat_id = '$editid'";
$edit_query = mysqli_query($con,$query);
}
while($row=mysqli_fetch_assoc($edit_query)) {
$cat_id = $row['cat_id'];
$cat_title = $row['cat_title'];
?>
<input value="<?php if(isset($editid)) {echo $cat_title;} ?>"
class="form-control" type="text" name="update">
<?php } } ?>
<?php
if(isset($_POST['update_submit']) && isset($_GET['edit'])) {
$editid = $_GET['edit'];
$updatetitle = $_POST['update'];
$query = "UPDATE categories SET cat_title='$updatetitle' where
cat_id='$editid'";
$update_query = mysqli_query($con,$query);
if (!$update_query) {
die('QUERY FAILED' . mysqli_error($con));
}
}
?>
</div>
<div class="form-group">
<input class="btn btn-primary" type="submit"
name="update_submit" value="Update Category">
</div>
</form>
</div>

Answer 1

In the POST condition, it's unable to identify $editid
Change this line:
if(isset($_POST['update_submit'])) {
To this:
if(isset($_POST['update_submit']) && isset($_GET['edit'])) {
$editid = $_GET['edit']; // Add this line
$updatetitle = $_POST['update'];
$query = "SELECT * FROM categories SET cat_title='$updatetitle' WHERE
cat_id = '$editid'"; //error line
$update_query = mysqli_query($con,$query);