c# - 将联接和分组依据从 SQL 转换为 LINQ

Question

我是 LINQ 新手，需要帮助转换此 SQL 代码：到 LINQ

    SELECT UserId_FK,COUNT(OrderId),SUM(Quantity)
    FROM Orders o
    JOIN OrderDetails od
    ON(o.OrderId = od.OrderId_FK)
    GROUP BY UserId_FK;

Answer 1

在没有看到您的架构文件的情况下，我将在这里猜测一下：

var userDetail =
    context.Orders
        .GroupBy(i => i.UserId_Fk)
        .Select(i => new {
                         UserId_Fk = i.Key,
                         OrderCount = i.Count(),
                         ProductQuantity = i.Sum(j => context.OrderDetails.Where(k=> k.OrderId_Fk == j.OrderId).Sum(k=> k.Quantity))
                      });