LINQ查询中的orderby Count（other_table）

Question

As mentioned in the Title, I want to orderby the result table using column of another table.

var products = (from p in db.Products
               join o in db.OrderDetails on p.ProductID equals o.ProductID
               orderby count(o.Quantity) <-- want to do something like this
               select p).Distinct().Take(8).ToList();

Below is the SQL Equivalent statement.

SELECT Products.ProductID FROM Products
INER JOIN OrderDetail on OrderDetail.ProductID = Products.ProductID
GROUP BY Products.ProductID
ORDER BY COUNT(OrderDetail.Quantity)

And I am getting desired results. But how can I do it using LINQ?

Answer 1

Just create a dictionary where the key is Product and value is calculated Quantity, and after that perform your query.

Or do it like this way:

var product = p in resultOfTheJoin
        let count = resultOfTheJoin.Quantity.Count()
        orderby count
        select p;

Answer 2

If i understand, you need a just like that. Pls try this:

       var query = (from p in db.Products
                     join o in db.OrderDetails on p.ProductID equals o.ProductID into orderTemp
                     select new type
                     {
                       Product_id = p.Product_id,
                       //set product attribtes,
                       OrderDetail_id = orderTemp.OrderDetail_id,
                       Quantity = orderTemp.Quantity,
                       // set OrderDetail attributtes

                     }.OrderBy(l => l.Quantity.Count()).ToList();