实体框架中的LINQ to SQL查询问题

Question

我有以下查询在LINQ to SQL中正常工作.现在我想将其更改为Entity Framework

var _sale = from emp in setupEmployees
            join sales in vwSaleTargets on emp.EmployeeID equals sales.EmployeeID
            join price in vwPeriodPricings
               on new { sales.SKUID, sales.PeriodID } 
               equals new { SKUID = (int?)price.SKUID, PeriodID = (int?)price.PeriodID }
            join sk in setupSKUs on sales.SKUID equals sk.SKUID
            join br in setupBrands on sk.BrandID equals br.BrandID
            where emp.EmployeeID == 123 && sales.StartDate.Year == 2012 
            select new { emp, sales, price, sk, br };

var lstSale = _sale.ToList(); //to avoid n+1 queries in case of grouping
var sale2 = from x in lstSale
            group x by new { x.sk, x.emp } into grouping
            select new 
            {
                 EmployeeName = grouping.Key.emp.EmployeeName,
                 SKUID = grouping.Key.sk.SKUID,
                 SKUName = grouping.Key.sk.Title,
                 MonthSale =(double?)grouping
                          .Where(x => x.sales.StartDate.Month == 2 && 
                                      x.sales.StartDate.Year == 2012)
                          .Select(t=>t.sales.SalesQuantity)
                          .Sum(t=>t.Value)?? 0,
                 MonthSaleValue = (double?)grouping
                          .Where(x => x.sales.StartDate.Month == 2 && 
                                      x.sales.StartDate.Year == 2012)
                          .Sum(x => x.sales.SalesQuantity * x.price.ExFactoryPrice)  
                             ?? 0,
            };
Console.WriteLine(sale2.OrderBy(x => x.SKUName).ToList());

在实体框架它给我结果像这样

Name SKUID SKUName MonthSale MonthSaleValue 
EMP1  36    SKU1     113     61375.95 
EMP1  17    SKU2     113     6656.83 
EMP1  18    SKU3     113     9984.68 
EMP1  19    SKU4     113     15169.12 

在L2S中我得到了正确的结果

Name SKUID SKUName MonthSale MonthSaleValue 
    EMP1  36    SKU1     74     40193.1 
    EMP1  17    SKU2     113     6656.83 
    EMP1  18    SKU3     461     40733.96
    EMP1  19    SKU4     2     268.48

问候

Answer 1

作为寻找答案的方法......

要按照@Jon Skeet的建议进行诊断,您需要简化它并查看您在lstSale中获得的内容,以便将LINQ to SQL与EntityFramework进行比较.

所以下面这些内容可能有所帮助(不一定在语法上正确,因为我没有检查所有的源对象,但是我只是查看查询并将其简化为可能的位置)

var _sale = from emp in setupEmployees
            join sales in vwSaleTargets on emp.EmployeeID equals sales.EmployeeID
            join price in vwPeriodPricings
               on new { sales.SKUID, sales.PeriodID } 
               equals new { SKUID = (int?)price.SKUID, PeriodID = (int?)price.PeriodID }
            join sk in setupSKUs on sales.SKUID equals sk.SKUID
            where emp.EmployeeID == 123 && sales.StartDate.Year == 2012 && sales.StartDate.Month == 2
            select new 
            { 
                EmployeeName = emp.EmployeeName, 
                StartDate = sales.StartDate,
                SalesQuantity = sales.SalesQuantity, 
                ExFactoryPrice = price.ExFactoryPrice, 
                SKUID = sk.SKUID,
                SKUName = sk.SKUName 
            };

var lstSale = _sale.ToList(); //to avoid n+1 queries in case of grouping

// Run through lstSale here
foreach(var item in lstSale)
{
  Console.WriteLine(item);
}

var sale2 = from x in lstSale
            group x by new { x.SKUID, x.EmployeeName } into grouping
            select new 
            {
                 EmployeeName = grouping.Key.EmployeeName,
                 SKUID = grouping.Key.SKUID,
                 SKUName = grouping.SKUName,
                 MonthSale =(double?)grouping
                          .Where(x => x.StartDate.Month == 2 && 
                                      x.StartDate.Year == 2012)
                          .Select(t=>t.SalesQuantity)
                          .Sum(t=>t.Value)?? 0,
                 MonthSaleValue = (double?)grouping
                          .Where(x => x.StartDate.Month == 2 && 
                                      x.StartDate.Year == 2012)
                          .Sum(x => x.SalesQuantity * x.ExFactoryPrice)  
                             ?? 0,
            };
Console.WriteLine(sale2.OrderBy(x => x.SKUName).ToList());

更改(可能并非全部有效):
1.删除了品牌,因为它未在第二个查询中使用(您可以在第一个查询中将其用作连接,但如果其部分限制则不添加到新类型)
2简化了第一个查询生成的匿名类型中包含的内容 - 如果您只消耗了部分emp/sales/price,那么它可以更清楚地说明发生了什么
.3.在第一部分中添加对SalesMonth的限制(什么你正在做第二个)因为这可能会减少你的数据,提高性能,让你专注于实际出错的地方(我已经保留了第二个SalesMonth限制)
4.我认为SKUID是sk的相关部分分组而不是所有对象都是必需的