LINQ - 左參數與參數

Question

可以有人請幫我一個SQL，我只是無法讓我的頭。在T-SQL，它看起來像這樣：

SELECT v.errandtype 
, COUNT(s.IVRTaskType) 
FROM V_ERRANDS v 
LEFT OUTER JOIN StatisticsRequest s 
    ON s.IVRTaskType = V.IVRTaskType 
    AND s.RegistrationDate >= '2014-03-24 00:00:00.000' 
    AND s.RegistrationDate <= '2014-03-24 23:59:59.000' 
    AND s.CountryID = 0 
GROUP BY v.errandtype 

但在LINQ ......那語言......所以嚇壞奇怪，我只是不明白這一點。

非常感謝這方面的幫助。

Answer 1

在LINQ你的要求將是這樣的：

var statisticsRequest = yourContext.StatisticsRequest.Where(s => 
    s.RegistrationDate >= new DateTime(2014,03,24) && 
    s.RegistrationDate <= new DateTime(2014,03,25) && 
    s.CountryID == 0); 

var results = 
    from v in yourContext.V_ERRANDS 
    group v by v.errandtype into g 
    join s in statisticsRequest on s.IVRTaskType = g.FirstOrDefault().IVRTaskType 
    select new { 
     s.IVRTaskType, 
     g.Count() 
    } 

Answer 2

• DefaultIfEmpty的左連接
• DateTime變量LINQ查詢外
• 匿名類型分組，這樣你就可以算其他桌子列

---

DateTime start = new DateTime(2014,03,24); 
DateTime end = new DateTime(2014,03,25); 

var query = from v in context.V_ERRANDS 
      from s in context.StatisticsRequest.Where(x => x.IVRTaskType == v.IVRTaskType) 
               .Where(x => x.RegistrationDate >= start && x.RegistrationDate < end) 
               .Where(x => x.CountryID == 0) 
               .DefaultIfEmpty() 
      group new { v, s} by v.errandtype into g 
      select new 
      { 
       errandtype = g.Key, 
       count = g.Select(x => x.s.IVRTaskType).Count(), 
      };