Question

这是我在SQL中正常工作的SQL查询：

select ld.FolderId, count(ld.LeadId) LeadID, sum(note.noteCount) NoteCount, count(ld.CallResultId) Calls 
from LeadsDetails ld 
    left join 
    (
        select lnh.LeadId, Count(lnh.NoteId) as noteCount 
        from [dbo].[LeadNoteHistory] lnh 
        group by lnh.LeadId
    )note
    on note.LeadId=ld.LeadId 
group by ld.FolderId

我试过了 -

var query = 
    from lead in _context.LeadsDetails
    join note in _context.LeadNoteHistories
    on lead.LeadId equals note.LeadId into g
    from notes in g.DefaultIfEmpty()
    group lead by lead.FolderId into grp
    select new
    {
        FolderId = g.FolderId,
        LeadID = g.LeadId,
        NoteCount = notes.NoteId,
        Call = lead.CallResultId
    };

无法获得正确的结果。请告诉我我做错了什么。

Answer 1

稍后您无法在select子句中访问变量'g'。你需要使用变量'grp'。您还需要修改最终组。我尝试修改，看看是否有效：

var query = 
    from lead in _context.LeadsDetails
    join note in _context.LeadNoteHistories
    on lead.LeadId equals note.LeadId into g
    from notes in g.DefaultIfEmpty()
    group new {lead,notes} lead by lead.FolderId into grp
    select new
    {
        FolderId = grp.Key,
        LeadID = grp.Count(),
        NoteCount = grp.Count(x=>x.notes!=null),
        Call = grp.Count()
    };

Answer 2

将SQL转换为LINQ，

将子选择转换为单独的变量
以LINQ子句顺序翻译每个子句，将monadic运算符（DISTINCT，TOP等）作为应用于整个LINQ查询的函数。
使用表别名作为范围变量。使用列别名作为匿名类型字段名称。
对多列使用匿名类型（new { }）
通过使用连接变量并从连接变量执行另一个from，然后.DefaultIfEmpty()来模拟左连接。

这是你的SQL翻译：

var rightside = from lnh in dbo.LeadNoteHistory
                group lnh by lnh.LeadId into lnhg
                select new { LeadId = lnhg.Key, noteCount = lnhg.Count() };

var ans = from ld in dbo.LeadsDetails
          join note in rightside on ld.LeadId equals note.LeadId into notej
          from note in notej.DefaultIfEmpty()
          group new { ld, note } by ld.FolderId into ldnoteg
          select new {
              FolderId = ldnoteg.Key,
              LeadID = ldnoteg.Select(lng => lng.ld.LeadId).Count(),
              NoteCount = ldnoteg.Select(lng => lng.note.noteCount).Sum(),
              Calls = ldnoteg.Select(lng => lng.ld.CallResultId).Count()
          };

我在SQL中保留了LeadID定义，但这对我来说并不合适。

任何人都可以帮助我将SQL转换为linq查询。我试过但失败了

2 个答案: