Simple update/edit of data not working with PHP/MySql - php

Question

I am trying to do a simple edit/update of my data in the database. But somehow it will not work.
So I am able to read out the saved data into the form. I also don't have any errors
I have stared at my code and googled for hours but I don't see where I might have made a mistake with my code.
The printed echo gives the following output which seems to be right:
HTML code:
<form id="formAddCategory" class="FrmCat" action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post">
<div class="form-group">
<!-- hidden id from tbl -->
<input type="hidden" name="hiddenId" value="<?php echo $hiddenID ?>" />
<label for="recipient-name" class="control-label">Category Name:</label>
<input type="text" class="form-control" id="recipient-name1" name="category" required="" value="<?php echo $category ?>" />
</div>
<button type="submit" id="btnEditCat" class="btn btn-danger" name="editCategory">Save Category</button>
</form>
Part of my php code to edit/update:
<?php
//edit/update data to db
if(isset($_POST['editCategory'])){
$categoryUpdate = mysqli_real_escape_string($con, $_POST['category']);
$categoryID = mysqli_real_escape_string($con, $_POST['hiddenId']);
$qry = "UPDATE tbl_Category SET category = $categoryUpdate WHERE category_id = $categoryID";
$result = mysqli_query($con, $qry);
echo $qry;
if($result){
header("Location: category.php");
}
}
?>

Answer 1

You need single quote ' to wrap your parameter:
$qry = "UPDATE tbl_Category SET category = '$categoryUpdate' WHERE category_id = '$categoryID'";

Answer 2

You should use single quotes (') for values
$qry = "UPDATE tbl_Category SET category = '$categoryUpdate' WHERE category_id = '$categoryID'";
Also you can use like this to avoid SQL injection (See here)
$stmt = $dbConnection->prepare('SELECT * FROM employees WHERE name = ?');
$stmt->bind_param('s', $name);
$stmt->execute();
$result = $stmt->get_result();
while ($row = $result->fetch_assoc()) {
// do something with $row
}