GROUP and SUM in Entity Framework

Question

I want to select sum of all (paid) prices of an order item for each customer. Here is SQL command:

SELECT c.name,SUM(oi.price * oi.count) from customer c
JOIN order o ON c.id=o.customer_id
JOIN order_item oi ON o.id=oi.order_id
JOIN bill b ON b.id=oi.bill_id
WHERE b.payment_id is NOT null
GROUP by c.name;

I don't know how to do this in EF. Example result:

John Smith  1500,2  
Allan Babel 202,0  
Tina Crown  3500,78

(comma is used as decimal point..because price is decimal value)

Answer 1

Your example result doesn't seem to match your SQL command, but i think you are looking for something like this:

var query = from c in context.Customers
            join o in context.Orders on c.id equals o.customer_id
            join oi in context.OrderItems on o.id equals oi.order_id
            join b in context.bill on oi.bill_id equals b.id
            where b.payment_id != null
            group oi by c.name into g
            select new
            {
              Name = g.Key,
              Sum = g.Sum(oi => oi.price * oi.count),
            }