mysqli insert query returning false

Question

function cart() {

    if(isset($_GET['add_cart'])){

        global $connect;

        $ip = getIp();
        $pro_id = $_GET['add_cart'];
        $check_pro = "SELECT * FROM cart WHERE ip_add = '$ip' AND p_id = '$pro_id'" ;
        $run_check = mysqli_query($connect, $check_pro);

        if(mysqli_num_rows($run_check)>0){
            echo "do a thing";
        }else {
            $insert_pro = "insert into cart (p_id,ip_add) values ('$pro_id','$ip')";
            $run_pro = mysqli_query($connect, $insert_pro);
            if($run_pro){
                echo "<script>window.open('index.php','_self')</script>";
            }
        }

    }

Im most likely missing something so obvious so thank you in advance.

Answer 1

The qty column doesn't have a default value, and you're not providing a value for it when you insert the new row. This will cause an error. You need to specify a value, eg 0 .

Also, since p_id is an INT column, you don't need to put the value in quotes.

$insert_pro = "insert into cart (p_id,ip_add, qty) values ($pro_id,'$ip', 0)";

But better would be to use a prepared statement to protect against SQL injection.

$insert_pro = $connect->prepare("insert into cart (p_id,ip_add, qty) values (?, ?, 0)");
$insert_pro->bind_param("is", $pro_id, $ip);
$run_pro = $insert_pro->execute();