Insert query echo success but not updating in mysql database table - php

Question

I am trying to fetch a cart array through foreach loop. I can fetch array items successfully and when i echo them it shows the correct values. But when i apply insert query for each item to enter in my database table, It does not insert any thing but it shows success. I have 4 tables named:
customers-->serial primary,name,email,password,address,phone,city
products-->productid primary,name,description,image,price
orders-->serial primary,date,customerid foreign key
order_detail-->orderid,productid,quantity,price,color,size
order_detail and orders table should be updated when i click on button.
Here is my code. Any suggestions will be appreciated.
Code
if (isset($_SESSION['login_email'])) {
$email = $_SESSION['login_email'];
//Insert values in order table. This works correctly!!
$query = mysqli_query($con, "SELECT serial FROM customers WHERE email = '$email'");
while ($row = mysqli_fetch_array($query, MYSQLI_ASSOC)) {
$cust_id = $row['serial'];
$date = date('Y-m-d');
$que = mysqli_query($con, "INSERT INTO orders VALUES('', '$date', '$cust_id')");
}
// Fetching serial from orders table. This also works correct.
$q = mysqli_query($con, "SELECT serial FROM orders WHERE customerid = '$cust_id'");
while ($row1 = mysqli_fetch_array($q, MYSQLI_ASSOC)) {
$serial = $row1['serial'];
echo $serial ."\n";
}
//Problem comes here. Here i am trying to insert values in order_details
foreach ($_SESSION['cart'] as $id => $value) {
$subtotal = $value['price'] * $value['quantity'];
$pid = $value['id'];
$quantity = $value['quantity'];
$color = $value['color'];
$size = $value['size'];
}
mysqli_query($con, "INSERT INTO order_detail VALUES ($serial, $pid, $quantity, $subtotal, $color, $size)");
if (true) {
echo "success";
} else {
echo"not success";
}
}

Answer 1

Did you already try this?
if( mysqli_query($con, "INSERT INTO order_detail VALUES ($serial, $pid, $quantity, $subtotal, $color, $size)") ){
echo "success";
} else {
echo"not success";
}
I Think you better can do the insert in this way:
INSERT INTO order_detail (column1, column2, column3,...)
VALUES (value1, value2, value3,...)