Question

我在VB中有以下查询，但我不知道如何将其翻译为C＃synatax

 Dim q = From c In db.Customers
        Group Join o In db.Orders On c.CustomerID Equals o.CustomerID Into orders = Group 
        Select New With {c.ContactName, .OrderCount = orders.Count()}

谢谢

Answer 1

实际上很容易。你只需要删除“组”：

var q = from c in db.Customers
        join o in db.Orders on c.CustomerID equals o.CustomerID into orders
        select new { c.ContactName, OrderCount = orders.Count() };

或者，如果您正在寻找lambda语法：

var q = db.Customers.GroupJoin(db.Orders,
                               o => o.CustomerID,
                               c => c.CustomerID,
                               (c, orders) =>
                                   new
                                   {
                                       c.ContactName, 
                                       OrderCount = orders.Count()
                                   });

Answer 2

Dim q = From c In db.Customers
    Group Join o In db.Orders On c.CustomerID Equals o.CustomerID Into orders = Group 
    Select New With {c.ContactName, .OrderCount = orders.Count()}

var q =
    from c in db.Customers
    join o in db.Orders on c.CustomerID equals o.CustomerID into orders
    select new {c.ContactName, .OrderCount = orders.Count()};

C＃相当于VB LINQ Query

2 个答案: