無法將SQL查詢轉換爲等效的LinqToEntities代碼？

Question

簡而言之： 一個簡單的總結這個問題的方法是，你可以在linq中的連接上應用一個條件嗎？

我有以下SQL查詢：

select cdm.cashID, cdm.DateTimeTillOpened, cdm.DateTimeTillClosed, o.OrderID, o.OrderDate 
from CashDrawsMonies cdm 
join Orders o on o.OrderDate >= cdm.DateTimeTillOpened 
       AND o.OrderDate <= cdm.DateTimeTillClosed 
join Users u on o.UserID = u.UserID 
where u.UserID = 'C3763CC6-D1C5-4EF3-9B83-F7AB3BF8827A' 
group by cdm.cashID, cdm.DateTimeTillOpened, cdm.DateTimeTillClosed, o.OrderID, o.OrderDate 
order by o.OrderDate desc 

替代SQL @

select * 
from CashDrawsMonies cdm 
where exists 
(
    select * 
    from Orders o 
    join Users u on o.UserID = u.UserID 
    where 
     o.OrderDate >= cdm.DateTimeTillOpened and 
     o.OrderDate <= cdm.DateTimeTillClosed and 
     u.UserID = 'C3763CC6-D1C5-4EF3-9B83-F7AB3BF8827A' 
) 

我可以轉換大多數查詢，但在LINQ的聯接它總是要平等關鍵字而不是像> =或< =這允許我在SQL中給連接添加條件。這是什麼讓我撓我的頭，然後如何轉換它呢？

我的LINQ到entites的代碼（C＃）模型建立爲：

Cache.Model.Orders 
Cache.Model.CashDrawMonies 
Cache.Model.Users 

欣賞的幫助。

嘗試1：

   var results = from o in Cache.Model.Orders 
          from c in Cache.Model.CashDrawMoneys 
          join u in Cache.Model.Users on o.UserID equals u.UserID 
          where c.DateTimeTillOpened >= o.OrderDate 
          && c.DateTimeTillClosed <= o.OrderDate 
          select c; 

嘗試2：

  var results = from c in Cache.Model.CashDrawMoneys 
          from o in Cache.Model.Orders 
          where c.DateTimeTillOpened >= o.OrderDate 
          && c.DateTimeTillClosed <= o.OrderDate 
          group c by new { c.cashID, c.DateTimeTillOpened, c.DateTimeTillClosed, o.OrderID, o.OrderDate, o.UserID } into temp 
          from t in temp 
          join u in Cache.Model.Users on t.UserID equals u.UserID 
          where t.UserID == selectedUser.UserID 
          select t; 

返回任何結果....：S

UPDATE：

我重新寫我的SQL，SQL的第二peiece確實我想知道到底是什麼。只需要某人爲我轉換它不知何故？

SQL版本2轉換使用Linqer：

from cdm in db.CashDrawMoneys 
where 
    (from o in db.Orders 
    join u in db.Users on o.UserID equals u.UserID 
    where 
     o.OrderDate >= cdm.DateTimeTillOpened && 
     o.OrderDate <= cdm.DateTimeTillClosed && 
     u.UserID == new Guid("C3763CC6-D1C5-4EF3-9B83-F7AB3BF8827A") 
    select new { 
     o, 
     u 
    }).FirstOrDefault() != null 
select new { 
    cdm.UserID, 
    cdm.DateTimeTillClosed, 
    cdm.DateTimeTillOpened, 
    cdm.LooseChange, 
    cdm.Fivers, 
    cdm.Tens, 
    cdm.Twenties, 
    cdm.Fifties, 
    cdm.IsOpen, 
    cdm.IsClosed, 
    cdm.ClosingValue, 
    cdm.OpeningValue, 
    cdm.cashID 
} 

編譯n但產生以下錯誤：「到DbIsNullExpression的參數必須指原語或引用類型」

Answer 1

第一次嘗試的連接看起來正確。但是你是否轉過了比較運算符？

where c.DateTimeTillOpened **>=** o.OrderDate && c.DateTimeTillClosed **<=** o.OrderDate

更新：

不能創建內LINQ2EF一個新的對象，因爲它不知道如何翻譯，爲SQL。

u.UserID == new Guid("C3763CC6-D1C5-4EF3-9B83-F7AB3BF8827A") 

您將有LINQ語句之前定義的GUID，然後使用變量

var gid = new Guid("C3763CC6-D1C5-4EF3-9B83-F7AB3BF8827A") 

from cdm in db.CashDrawMoneys 
where 
    (from o in db.Orders 
    join u in db.Users on o.UserID equals u.UserID 
    where 
    o.OrderDate >= cdm.DateTimeTillOpened && 
    o.OrderDate <= cdm.DateTimeTillClosed && 
    u.UserID == gid 

Answer 2

下面是我設法：

   var results = from cdm in Cache.Model.CashDrawMoneys 
          where (from o in Cache.Model.Orders 
           join u in Cache.Model.Users on o.UserID equals u.UserID 
           where o.OrderDate >= cdm.DateTimeTillOpened && o.OrderDate <= cdm.DateTimeTillClosed && 
            u.UserID == selectedUser.UserID 
           select o).FirstOrDefault() != null 
          select cdm; 

這是非常接近你有什麼，也不用擔心這個GUID，因爲它已經爲我創建了，因爲我有一個'selectedUser'對象。

最後一行可能是：

        select o).Any() 
          select cdm; 

但是我不會大驚小怪，我得到了兩個變化，但我的第一個版本，我也會堅持。