What will be LINQ MVC query equivalent to given SQL query?

Question

I have written an SQL query which works fine. I need its equivalent query in LINQ MVC.

select sum(od.QUANTITY*od.PRODUCT_PRICE)
 from ORDERS as o 
 inner join ORDER_DETAILS as od
 on o.ID = od.ORDER_ID where o.IS_DELIVERED = 1
 AND o.IS_CANCELED = 0;

I tried to form it myself and ended up with the query mentioned below, but it's not working for me;

var sum = from order in dbContext.ORDERS
          join orderDetails in dbContext.ORDER_DETAILS
          on order.ID equals orderDetails.ORDER_ID
          where order.IS_DELIVERED == true && order.IS_RETURNED_BACK == false
          select new { sum = dbContext.ORDER_DETAILS.Sum(od => od.QUANTITY * od.PRODUCT_PRICE) };

Answer 1

If your DbContext has proper relational mappings, the below code works

dbContext.ORDERS.ORDER_DETAILS
     .Where(x => x.IS_CANCELLED == 0 && o.IS_RETURNED_BACK == false)
     .Sum(od => od.PRODUCT_PRICE)

If it doesn't you need to use join

var result = (from o in dbContext.ORDERS
join od in dbContext.ORDER_DETAILS
  on o.ID  equals od.ORDER_ID
where o.IsCancelled == 0 && && o.IS_RETURNED_BACK == false
select od.PRODUCT_PRICE).Sum();

Answer 2

Is this what you meant to do? This will create a list of order detail total and then sum the list to give you a value.

   var sum = (from order in dbContext.ORDERS
                  join orderDetails in dbContext.ORDER_DETAILS
                  on order.ID equals orderDetails.ORDER_ID
                  where order.IS_DELIVERED == true && order.IS_RETURNED_BACK == false
                  select new { orderDetailTotal = od.QUANTITY * od.PRODUCT_PRICE) }).Sum(x => x.orderDetailTotal);

Answer 3

Ideally, the ORDERS object should have a list of ORDER_DETAILS if done with proper relational mappings. Also the IS_DELIVERED and IS_RETURNED_BACK should be Booleans if mapped properly. In that case, you don't need an explicit join and your C# LINQ can be as simple as:

var sum = (from o in dbContext.ORDERS
           where o.IS_DELIVERED && !o.IS_RETURNED_BACK
           select new { Total = o.ORDER_DETAILS.QUANTITY * o.ORDER_DETAILS.PRODUCT_PRICE }
          ).Sum(x => x.Total);

Also, ideally the objects should've been named in pascal-case and without the underscores.

Answer 4

You don't need select clause, you can use Sum function on query result and specify lambda expression for field calculation you need.

var sum = (from order in dbContext.ORDERS
                  join orderDetails in dbContext.ORDER_DETAILS
                  on order.ID equals orderDetails.ORDER_ID
                  where order.IS_DELIVERED == true && order.IS_RETURNED_BACK == false).Sum(x=> x.QUANTITY * x.PRODUCT_PRICE)