Calculating the SUM of (Quantity*Price) from 2 different tables - sql

Question

I have two tables as follows
PRODUCT table
Id | Name | Price
And an ORDERITEM table
Id | OrderId | ProductId | Quantity
What I'm trying to do is, calculate the subtotal price for each product (Quantity*Price) then SUM the TOTAL value for the entire order..
I'm trying something like this
SELECT Id, SUM(Quantity * (select Price from Product where Id = Id)) as qty
FROM OrderItem o
WHERE OrderId = #OrderId
But of course that doesn't work :)
Any help appreciated!
EDIT: I only want to show the grand total for the entire order, so basically the sum of Quantity*Price for every row in OrderItem. Here's some sample data.
Sample Data
TABLE Product
Id Name Price
1 Tomatoes 20.09
4 Cucumbers 27.72
5 Oranges 21.13
6 Lemons 20.05
7 Apples 12.05
Table OrderItem
Id OrderId ProductId Quantity
151 883 1 22
152 883 4 11
153 883 5 8
154 883 6 62
M

Answer 1

Use:
SELECT oi.orderid,
SUM(oi.quantity * p.price) AS grand_total,
FROM ORDERITEM oi
JOIN PRODUCT p ON p.id = oi.productid
WHERE oi.orderid = #OrderId
GROUP BY oi.orderid
Mind that if either oi.quantity or p.price is null, the SUM will return NULL.

Answer 2

i think this - including null value = 0
SELECT oi.id,
SUM(nvl(oi.quantity,0) * nvl(p.price,0)) AS total_qty
FROM ORDERITEM oi
JOIN PRODUCT p ON p.id = oi.productid
WHERE oi.orderid = #OrderId
GROUP BY oi.id

Answer 3

I think this is along the lines of what you're looking for. It appears that you want to see the orderid, the subtotal for each item in the order and the total amount for the order.
select o1.orderID, o1.subtotal, sum(o2.UnitPrice * o2.Quantity) as order_total from
(
select o.orderID, o.price * o.qty as subtotal
from product p inner join orderitem o on p.ProductID= o.productID
where o.orderID = #OrderId
)as o1
inner join orderitem o2 on o1.OrderID = o2.OrderID
group by o1.orderID, o1.subtotal

Answer 4

select orderID, sum(subtotal) as order_total from
(
select orderID, productID, price, qty, price * qty as subtotal
from product p inner join orderitem o on p.id = o.productID
where o.orderID = #orderID
) t
group by orderID

Answer 5

I had the same problem as Marko and come across a solution like this:
/*Create a Table*/
CREATE TABLE tableGrandTotal
(
columnGrandtotal int
)
/*Create a Stored Procedure*/
CREATE PROCEDURE GetGrandTotal
AS
/*Delete the 'tableGrandTotal' table for another usage of the stored procedure*/
DROP TABLE tableGrandTotal
/*Create a new Table which will include just one column*/
CREATE TABLE tableGrandTotal
(
columnGrandtotal int
)
/*Insert the query which returns subtotal for each orderitem row into tableGrandTotal*/
INSERT INTO tableGrandTotal
SELECT oi.Quantity * p.Price AS columnGrandTotal
FROM OrderItem oi
JOIN Product p ON oi.Id = p.Id
/*And return the sum of columnGrandTotal from the newly created table*/
SELECT SUM(columnGrandTotal) as [Grand Total]
FROM tableGrandTotal
And just simply use the GetGrandTotal Stored Procedure to retrieve the Grand Total :)
EXEC GetGrandTotal