I have created a database with table categories. I create a functionality to add delete read and edit categories. But reading adding and deleting works fine but editing shows an error.
<div id="wrapper">
<?php include "includes/admin_navigation.php"?>
<div id="page-wrapper">
<div class="container-fluid">
<!-- Page Heading -->
<div class="row">
<div class="col-lg-12">
<h1 class="page-header">
Blank Page
<small>Subheading</small>
</h1>
<div class="col-lg-6">
<?php // add category
if (isset($_POST['submit'])) {
$cat_name = $_POST['cat_name'];
if ($cat_name == "" || empty($cat_name)) {
echo "this field should not be empty";
} else {
$query = "INSERT INTO categories(cat_name) VALUE('$cat_name')";
$create_category = mysqli_query($connection, $query);
if(!$create_category){
die("QUERY FAILED" . mysqli_error($connection));
}
}
}
?>
<form action="categories.php" method="post">
<div class="form-group">
<label for="cat_name">Enter category name</label>
<input class="form-control" type="text" name="cat_name">
</div>
<div class="form-group">
<input class="btn primary" type="submit" name="submit" value="Add category">
</div>
</form>
<form action="categories.php" method="post">
<?php // edit category
if (isset($_GET['edit'])){
$cat_id = $_GET['edit'];
$query = "SELECT * FROM categories WHERE id = {$cat_id}";
$select_categories_id = mysqli_query($connection, $query);
while ($row = mysqli_fetch_assoc($select_categories_id)){
$cat_title = $row['cat_name'];
$the_cat_id = $row['id']; ?>
<div class="form-group">
<label for="cat_name">Edit category name</label>
<input value="<?php if(isset($cat_title)) {echo $cat_title;} ?>" class="form-control" type="text" name="cat_name">
</div>
<div class="form-group">
<input class="btn primary" type="submit" name="update_category" value="Edit category">
</div>
<?php }
}
if (isset($_POST['update_category'])) {
$update_cat_title = $_POST['cat_name'];
$query = "UPDATE categories SET cat_name = {$update_cat_title} WHERE id = {$cat_id}"; // the problem is with $cat_id (on videolesson everything works fine but on my local pc becomes next error - Notice: Undefined variable: the_cat_id in /var/www/html/wordpress/cms/CMS_TEMPLATE/admin/categories.php on line 75)
$update_query = mysqli_query($connection, $query);
if(!$update_query){
die("QUERY FAILED" . mysqli_error($connection));
}
}
?>
</form>
</div>
<div class="col-lg-6">
<table class="table table-bordered table-hover">
<thead>
<tr>
<th>ID</th>
<th colspan="3">CATEGORY TITLE</th>
</tr>
</thead>
<tbody>
<?php // delete category
$query = "SELECT * FROM categories"; // find categories query
$select_categories_sidebar = mysqli_query($connection, $query);
while ($row = mysqli_fetch_assoc($select_categories_sidebar)){
$cat_title = $row['cat_name'];
$cat_id = $row['id'];
echo "
<tr>
<td>
{$cat_id}
</td>
<td>
{$cat_title}
</td>
<td>
<a href='categories.php?edit={$cat_id}'>Edit</a>
</td>
<td>
<a href='categories.php?delete={$cat_id}'>Delete</a>
</td>
</tr>
";
}
if (isset($_GET['delete'])) {
$del_cat_id = $_GET['delete'];
$query = "DELETE FROM categories WHERE id = {$del_cat_id} "; // delete category
$delete_query = mysqli_query($connection, $query);
header("location: categories.php");
}
?>
</tbody>
</table>
</div>
</div>
</div>
<!-- /.row -->
</div>
<!-- /.container-fluid -->
</div>
<!-- /#page-wrapper -->
</div>
