如何在Linq查询中加入4个表格

Question

我使用SQL 2014和2013以及EF4。

我有4个表中的数据库：

• SupplierPurchaseAlarm
• Order
• OrderDetail
• Product

我想加入这些表格并获得NewOrderCount，AllSellProductCount和SumOf Price in orderDetail。

我写了这个代码，但它不为我工作：

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

我解决它......

  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;