Question

我正在尝试将以下SQL转换为LINQ表达式

SELECT    COUNT(ID) AS Count, MyCode
FROM      dbo.Archive
WHERE     DateSent>=@DateStartMonth AND DateSent<=@DateEndMonth
GROUP BY  MyCode

我一直试图关注这个网页作为例子：
Converting SQL containing top, count, group and order to LINQ (2 Entities)

到目前为止，我得到了这个，但我仍然坚持理解新的部分

var res = (from p in db.Archives
           where (p.DateSent>= dateStartMonth) && (p.DateSent< dateToday)
           group p by p.MyCode into g
           select new { ??????MyCode = g.something?, MonthlyCount= g.Count() });

提前感谢您的帮助

的更新：
你能解释一下g.Key是什么吗？我不明白那个变量来自哪里或它是指什么？我的意思是如果我分组4个不同的东西？我如何参考每一个？

var res = from archive in db.Archives
      where archive.DateSent >= dateStartMonth &&
            archive.DateSent < dateToday
      group archive by archive.MyCode, archive.Extra into archiveGrp
      select new 
      { 
           MyCode = archiveGrp.Key, 
           Extra = archiveGrp.???
           MonthlyCount = archiveGrp.Count() 
      };

Answer 1

下面的LINQ语句应该有效：

var res = from archive in db.Archives
          where archive.DateSent >= dateStartMonth &&
                archive.DateSent < dateToday
          group archive by archive.MyCode into archiveGrp
          select new 
          { 
               MyCode = archiveGrp.Key, 
               MonthlyCount = archiveGrp.Count() 
          };

请注意，Key property将包含您分组的属性的值，在本例中为MyCode。

Answer 2

from p in archive
where p.DateSent >= dateStartMonth && p.DateSent < dateToday
group p by p.MyCode into g
select new { Count = g.Count(), MyCode = g.Key  }

生成与Linqpad中的Sql相同的输出

使用count将SQL转换为linq表达式

2 个答案: