LINQ左连接不返回与T-SQL左连接相同 [英] LINQ Left join not returning the same as T-SQL left join

问题描述

嗨


我正在研究这个解决方案，我想将以下T-SQL转换为linq查询

选择
 
 SI.Spreadpublicationcode 
，SI.spreadpage 
，SI.shotsequence 
，si.itemnumbershort 
 来自 #HacksTemp   hck 
 left  join  #TempSource SI on 
 hck.Publication = SI.Spreadpublicationcode AND 
 hck.Page = SI.spreadpage AND 
 hck.Shot = SI.shotsequence and 
 hck.ItemNumberShort = SI.ItemNumberShort 
 其中 si.spreadpublicationcode    null  

我所做的是

 var diff = from c in check 
在源代码中加入新的{c.ItemNumberShort，c.Page，c.Shot，c.Publication}等于new {s.ItemNumberShort， s.Page，s.Shot，s.Publication} 
从di.DefaultIfEmpty（）中的s到di 
 
其中s == null 
 select s; 
 
返回diff.ToList< Hack>（）; 

但是我的输出非常不同T-sql我得到了39行，但在我的linq查询中，它返回完整的检查，即8780原始数据，我使用的数据都是相同的



如果有人的话用我在LINQ中错过的东西纠正我



谢谢

解决方案

检查这些：

使用LINQ进行左连接，右连接 [ ^ ]

如何：执行左外连接（C＃编程指南） ） [ ^ ]

Hi
I am working on a this solution where i wanted to convert the following T-SQL to linq query

Select

    SI.Spreadpublicationcode
    ,SI.spreadpage
    ,SI.shotsequence
    ,si.itemnumbershort
    from #HacksTemp as hck
    left join #TempSource SI  on
    hck.Publication = SI.Spreadpublicationcode AND
    hck.Page = SI.spreadpage AND
    hck.Shot = SI.shotsequence and
    hck.ItemNumberShort = SI.ItemNumberShort
  where si.spreadpublicationcode is null

what i have done so for is

var diff = from c in check
    join s in source on new { c.ItemNumberShort, c.Page, c.Shot, c.Publication } equals new { s.ItemNumberShort, s.Page, s.Shot, s.Publication }
    into di
    from s in di.DefaultIfEmpty()
    where s == null
    select s;

    return diff.ToList<Hack>();

but the out put is very differnt on my T-sql i get 39 rows back but on my linq query it return the full check i.e 8780 raws i am using the data in both are the same

appricate if someone correnct me with what i have missed out in my LINQ

thanks

解决方案

Check these:
Left Join, Right Join Using LINQ[^]
How to: Perform Left Outer Joins (C# Programming Guide)[^]

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