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我创建了一个EF Join。 frameStart
有19条记录,frameEnd
有42条记录,但是当我做连接时(framing
),只有10条记录。我相信只有10条记录,因为它正在连接可以用匹配键组合的记录。代码如下。我如何做到这一点,以便在加入时,我可以得到所有记录的列表,甚至是那些不匹配的记录?C#EntityFramework加入所有记录
public class s84_Report_FrameLabor
{
public int CustomerID { get; set; }
public string CustomerName { get; set; }
public int SubdivisionID { get; set; }
public string SubdivisionName { get; set; }
public int LotNumber { get; set; }
public string InstallManagerStart { get; set; }
public string InstallManagerComplete { get; set; }
public DateTime FrameLaborStart { get; set; }
public DateTime FrameLaborComplete { get; set; }
public int Duration { get; set; }
/*
Frame Labor Start ------ Product ID: 26
Frame Labor Complete ------ Product ID: 8
*/
public static List<s84_Report_FrameLabor> getDurationReport()
{
using (var context = PrimaryConnection.returnNewConnection())
{
var frameStart = (from c in context.s84_Schedule
where c.ProductID == 26 && c.Completed == false
select new
{
CustomerID = c.CustomerID,
CustomerName = c.s84_Customer.CustomerName,
SubdivisionID = c.SubdivisionID,
SubdivisionName = c.s84_Subdivision.SubdivisionName,
LotNumber = c.LotNumber,
FrameLaborStart = c.CustomerExpectedDate
}).ToList();
var frameEnd = (from c in context.s84_Schedule
where c.ProductID == 8 && c.Completed == false
select new
{
CustomerID = c.CustomerID,
SubdivisionID = c.SubdivisionID,
LotNumber = c.LotNumber,
FrameLaborComplete = c.CustomerExpectedDate
}).ToList();
var framing = from c in frameStart
join e in frameEnd on new { c.CustomerID, c.SubdivisionID, c.LotNumber } equals new { e.CustomerID, e.SubdivisionID, e.LotNumber }
select new s84_Report_FrameLabor
{
CustomerID = c.CustomerID,
CustomerName = c.CustomerName,
SubdivisionID = c.SubdivisionID,
SubdivisionName = c.SubdivisionName,
LotNumber = c.LotNumber,
FrameLaborStart = c.FrameLaborStart,
FrameLaborComplete = e.FrameLaborComplete,
Duration = (e.FrameLaborComplete - c.FrameLaborStart).Days
};
return framing.ToList();
}
}
}
搜索实体框架左连接,你会发现DefaultIfEmpty函数。这应该可以解决你的问题。 – Andre
例如[左外连接LINQ to Entities](http://www.progware.org/Blog/post/Left-Outer-Join-in-LINQ-to-Entities-%28for-Entity-Framework-4%29 .aspx) – stuartd
是的。听起来就像你想要一个左连接。查看[LINQ中的左外连接](http://stackoverflow.com/questions/3404975/left-outer-join-in-linq)。我特别喜欢这个答案,“可读性更好的左外连接可以这样写”。 –