如何在Linq查询中加入4表

Question

我使用SQL 2014和vs 2013以及EF4。

我在数据库中有4个表：

• SupplierPurchaseAlarm
• Order
• OrderDetail
• Product

我希望加入这些表格并在NewOrderCount中获取AllSellProductCount，SumOf Price和orderDetail。

我写了这段代码，但它对我不起作用：

public ShowAllSupplierAlarmInfo GetAllMsgAndAlarmCount(long suplierId)
    {
        try
        {
            var supplierPurchaseList = _db.Context.SuplierPurchaseAlarms.Where(x => x.SuplierId == suplierId).AsQueryable();
            var query = from supPurchaseMsg in supplierPurchaseList
                join ord in _db.Context.Orders on supPurchaseMsg.OrderId equals ord.OrderID
                join ordDetail in _db.Context.OrderDetails on ord.OrderID equals ordDetail.OrderID
                join prd in _db.Context.Products on ordDetail.ProductID equals prd.ProductID
                where prd.SupplierID==supPurchaseMsg.SuplierId
                where
                    ord.IsPayed && ord.CurentOrderState == (int) EnumCurrentOrderState.ProductIsPreparingToSend ||
                    ord.CurentOrderState == (int) EnumCurrentOrderState.TheProductIsWaitingForApprovalBySuppliers

                group ordDetail by ord
                into j
                select new
                {
                    OrderCount = j.GroupBy(x => x.Order.OrderID).Count(),
                    SellProductCount = j.Sum(x => x.Quantity),
                    AllOrderCount = j.Count(x => x.Order.IsPayed),
                    profit = j.Sum(x=>x.UnitPrice*x.Quantity)
                };
            var res = new ShowAllSupplierAlarmInfo()
              {
                  PurchaseAlertCount = supplierPurchaseList.Count(x => x.TypeId==(int)AlarmTypeId.Warning)
              };

            foreach (var prd in query)
            {
                res.SellCount += prd.SellProductCount;
                res.NewOrderCount += prd.OrderCount;
                res.AllOrderCount += prd.AllOrderCount;
                res.Profit = prd.profit;
            }
            return res;
        }

Answer 1

我解决了......

            var query = _db.Context.Orders.GroupJoin(_db.Context.OrderDetails, ord => ord.OrderID,
                orddetail => orddetail.OrderID, (ord, ordd) => new
                {
                    ord.CurentOrderState,
                    ord.CreationDate,
                    ord.TotalPriceAfterUsingCoupon,
                    ord.OrderID,
                    OrDetail = ordd.Join(_db.Context.Products, x => x.ProductID, x => x.ProductID,
                        (orddeta, prod) => new OrDetail { Productname = prod.ProductName, UnitPrice = orddeta.UnitPrice, Quantity = orddeta.Quantity }
                        )
                }).ToList();

            var result =  query.Select(item => new ShowAllProductInUserOrder()
            {
                OrderId = item.OrderID, CurentOrderState = item.CurentOrderState, CreationDate = item.CreationDate, TotalPriceAfterUsingCoupon = item.TotalPriceAfterUsingCoupon, OrderDetail = item.OrDetail.ToList()
            }).ToList();
            return result;