在C＃翻译LINQ表达式

Question

我试图把这段代码转换：

var query2 = from b in db.MU_Reports 
      join downtime in db.Downtime_Reports on b.Shift equals downtime.Shift 
      where downtime.Downtime_Code.Equals("9185") 
      group downtime by new { b.Date, b.Shift, b.Machine_Number, b.MU } into g 
      select new 
      { 
       Date = g.Key.Date, 
       Shift = g.Key.Shift, 
       Machine = g.Key.Machine_Number, 
       MU = g.Key.MU, 
       No_Work_Hours = g.Sum(x => x.Total_DownTime) 
      }; 

要看起来像这样之一：

var query = db.MU_Reports.Join(db.Downtime_Reports, b=> b.Shift, c=> c.Shift, (b , c) => new { b, thisshift = c }) 
      .Where(n => n.thisshift.Down_TIme_Codes.Equals("9185")) 
      .GroupBy(d=> new { d.b.Date, d.b.Shift, d.b.Machine_Number, d.b.MU }, d => d.b) 
      .Select (g=> new 
      { 
       Date = g.Key.Date, 
       Shift = g.Key.Shift, 
       Machine = g.Key.Machine_Number, 
       MU = g.Key.MU, 
       No_Work_Hours = g.Sum(i => i.Total_DownTime) 
      }).ToList(); 

正如你看到的我是非常密切的。我唯一的问题是最后的声明No_Work_Hours = g.Sum(i => i.Total_DownTime)它试图从db.MU_Reports得到Total_DownTime，但它需要来自db.Downtime_Reports。我是c＃的新手，并且正在做这个来理解我创建的程序更好。

Answer 1

您对GroupBy的第二个参数应该是d => d.thisshift而不是d => d.b。对应于group downtime by，但这么做d => d.b这就像你正在做group b by

var query = db.MU_Reports 
    .Join(
     db.Downtime_Reports, 
     b=> b.Shift, 
     c=> c.Shift, 
     (b , c) => new { b, thisshift = c }) 
    .Where(n => n.thisshift.Down_TIme_Codes.Equals("9185")) 
    .GroupBy(
     d=> new { d.b.Date, d.b.Shift, d.b.Machine_Number, d.b.MU }, 
     d => d.thisshift) 
    .Select (g=> new 
    { 
     Date = g.Key.Date, 
     Shift = g.Key.Shift, 
     Machine = g.Key.Machine_Number, 
     MU = g.Key.MU, 
     No_Work_Hours = g.Sum(i => i.Total_DownTime) 
    }) 
    .ToList();