Не могу разобраться с кодом

//Добавляем категорию
if (isset($_GET['action']) and $_GET['action'] == 'add' and isset($_POST['category_name']) and isset($_POST['category_description'])) {
$category_name = $_POST['category_name'];
$category_description = nl2br($_POST['category_description']);
$sql_edit = "INSERT INTO item_category (id_category, category_name, category_description)
  VALUES (NULL, '$category_name', '$category_description')";
$query_edit = mysqli_query($connect_db, $sql_edit);
if (!$query_edit) {echo "<div class=\"alert alert-error\">Категорию добавить не удалось!</div>";} else {echo "<div class=\"alert alert-success\">Категория успешно добавлена!</div>";}
}
//Добавляем категорию
 
$sql_category = 'SELECT
  item_category.id_category,
  item_category.category_description,
  item_category.category_name
FROM item_category';
$query_category = mysqli_query($connect_db, $sql_category);
 
$sql_category2 = 'SELECT
  item_category.id_category,
  item_category.category_description,
  item_category.category_name
FROM item_category';
$query_category2 = mysqli_query($connect_db, $sql_category2);
 
$sql_category3 = 'SELECT
  item_category.id_category,
  item_category.category_description,
  item_category.category_name
FROM item_category';
$query_category3 = mysqli_query($connect_db, $sql_category3);