复杂SQL到LINQ在C＃

Question

林完全新手在LINQ和Lamda表达式。 我有来自多个数据库表中检索信息有点复杂的SQL语句：

SELECT A.OrderID, A.FORMJDENO, A.Title, B.Descr, C.Code, C.Descr, D.ModificationDate from OrderForm A 
LEFT JOIN OrderPriority B ON A.OrderPriorityID = B.OrderPriorityID 
LEFT JOIN StockClass C ON A.StockClassID = C.StockClassID 
LEFT JOIN AuditTrailLog D ON A.OrderID = D.ObjectID 
WHERE D.ColumnInfoID= 487 AND D.OldValue='1' AND D.NewValue='2' AND A.FormStatus=2 AND A.FormType=3 AND B.OrderPriorityID=1000001 AND C.StockClassID=1000002 
AND A.DeptID IN 
    (SELECT DeptID FROM Department WHERE InstID = 1000006) 
AND DATEDIFF(m,D.ModificationDate, A.VendorDeliveryDate) >= 3 

我已经有LINQ差不多完成了，使用.Contains()法取代WHERE...IN SQL条款，但我需要一些帮助，使德joins限制结果基于属于其他表的值，并在LINQ中使用DATEDIFF等效值。 这就是我已经得到的并且工作正常，但显然它不限制上述SQL语句的结果。我尝试了几种方式，但没有成功。我需要相当于LINQ

UPDATE：

最后我能得到它的工作。这是检索与SQL语句相同记录的最终LINQ。非常感谢@Gert阿诺德：

var valid = dba.OrderForm 
      .Where(q => q.FormType == 3 
         && q.FormStatus == 2 
         && q.OrderPriority.OrderPriorityID == orderpriorityID 
         && q.StockClass.StockClassID == stockclassID 
         && dba.AuditTrailLog.Where(log => q.OrderID==log.ObjectID) 
           .Any(log => log.ColumnInfoID == 487 
              && log.OldValue == "1" 
              && log.NewValue == "2" 
              && EntityFunctions.DiffMonths(log.ModificationDate,  
                   q.VendorDeliveryDate) >= period) 
         && departments.Contains(q.DeptID)); 

Answer 1

我觉得这是它：

dba.OrderForm.Where(q => q.FormType == 3 
    && q.FormStatus == 2 
    && q.OrderPriority.OrderPriorityID == 1000001 
    && q.StockClass.StockClassID == 1000002 
    && q.AuditTrailLogs 
     .Any(log => log.ColumnInfoID == 487 
       && log.OldValue == "1" 
       && log.NewValue == "2" 
       && EntityFunctions.DiffMonths(log.ModificationDate, 
               q.VendorDeliveryDate) >= 3) 
    && departments.Contains(q.DeptID)); 

我假设你有（或者可以创建）导航属性OrderTable.AuditTrailLogs。

没有导航属性可以使用

&& dba.AuditTrailLogs.Where(log => q.OrderID == log.ObjectID).Any(...