php shopping cart -group by selection and get the total - php

Question

My question is a little bit long...
This is the is the first picture for my question:
---Here it is the query how I make the selection:
$costumer_name=$_SESSION['p_user'];
$date=date("y-m-d");
$query_8="select * from orders
where costumer_name='$costumer_name' && date='$date'
order by product_id desc";
$result_8=mysql_query($query_8);
---As you see, the selection table needs a group by query and here is that query and the result:
$costumer_name=$_SESSION['p_user'];
$date=date("y-m-d");
$query_8="select * from orders
where costumer_name='$costumer_name' && date='$date'
group by product_id desc";
$result_8=mysql_query($query_8);
---Here it is how I get the SUM:
$query_9="select SUM(totali) as totali from orders where costumer_name='$costumer_name' && date='$date'";
$result_9=mysql_query($query_9);
$row_9=mysql_fetch_array($result_9);
$totali=$row_9['totali'];
---And finaly the problem:
1.How to count the number of orders with the same product_id(sasia)?
2.Get the first total of -cmimi and -sasia?
3.Get the final total?
Thank you

Answer 1

first of all i think there is better solution then every time when somebody click add to cart button to always insert new row in the database. If product is already there you should update quantity by +1, that way you will have only one row of one products instead of 3. I don't know exactly how your database look but here is an idea how you could do that:
CREATE PROCEDURE add_to_cart(IN in_cart_id INT, IN in_product_id...)
BEGIN
DECLARE quant INT;
SELECT quantity
FROM cart
WHERE cart_id = in_cart_id
AND product_id = in_product_id
INTO quant;
IF quant IS NULL then
INSERT INTO cart....
ELSE
UPDATE cart
SET quantity = quantity + 1
WHERE cart_id = in_cart_id
AND product_id = in_product_id;
END IF;
END$$
I think that is much better solution but if you want to do that the way you started then here is a way to do that:
SELECT productId, name, price, COUNT(quantity) as quantity, (price * COUNT(quantity)) as total
FROM where-ever-you store data
WHERE expression
GROUP BY productId;
that is answer on two your question, for the third total sum you need to write separate SELECT statement
SELECT SUM(price * quantity) as total_sum
FROM where-ever-you-store-data
WHERE expression if needed...