Warning: Undefined array key "id" in T:\Xampp\htdocs\shoe\product-detail.php on line 9

Fatal error: Uncaught mysqli_sql_exception: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '' at line 1 in T:\Xampp\htdocs\shoe\repository\shoeRepository.php:20 Stack trace: #0 T:\Xampp\htdocs\shoe\repository\shoeRepository.php(20): mysqli_query(Object(mysqli), 'select s.id as ...') #1 T:\Xampp\htdocs\shoe\product-detail.php(9): ShoeRepository->getById(NULL) #2 {main} thrown in T:\Xampp\htdocs\shoe\repository\shoeRepository.php on line 20