SQL到LINQ组通过

Question

我试图将以下SQL转换为LINQ。我已经通过变量获得了1组的成功，但无法让这个工作。任何帮助，将不胜感激。

select ContactID, EventID, Count=count(*) 
    from ScanLogs s, Exhibits e 
    where s.ExhibitID = e.ExhibitID 
    group by s.ContactID, e.EventID 

结果看起来是这样的：

ContactID EventID Count 
300009 2000048 2 
300009 2000096 1 
300036 2000096 1 

Answer 1

我相信，这将做到这一点：

var query = from s in ScanLogs 
      from e in Exhibits 
      where s.ExhibitID == e.ExhibitID 
      group 1 by new { s.ContactID, e.EventID } into g 
      select new { g.Key.ContactID, g.Key.EventID, Count = g.Count() }; 

这不是什么重要的分组（1在这种情况下），你只是在计算有多少。

但是我可能会使用连接。它应该是等效的。

var query = from s in ScanLogs 
      join e in Exhibits on s.ExhibitID equals e.ExhibitID 
      group 1 by new { s.ContactID, e.EventID } into g 
      select new { g.Key.ContactID, g.Key.EventID, Count = g.Count() }; 

Answer 2

另一个varian使用连接和group by。

var query = from c in ScanLogs 
      join d in Exhibits on c.ExhibitID equals d.ExhibitID 
      group new{ 
      g.Key.ContactID, 
      g.Key.EventID, 
      Count = g.Count() 
      } 
      by new { 
       c.ContacID, d.EventID 
      } into g 
      select g;