左外连接在实体数据模型asp.net [英] Left Outer Join in Entity Data Model asp.net

问题描述

如何实现左外Linq中加入到实体框架。不支持DefaultIfEmpty功能。
请提供一个例子。

how to implement Left outer join in Linq to entity framework. DefaultIfEmpty function is not supported. please provide an example.

推荐答案

这工作在.NET 3.5。当你加入无，从做与FirstorDefault功能组合，它会给你你正在寻找左连接表的行。如果你想多行，只需使用其中（），而不是..希望这会有所帮助。

This works in .NET 3.5. When you join without doing "from" in combination with the FirstorDefault function, it will give you the row you are looking for in the left joined table. If you want multiple rows, just use where() instead.. Hope this helps.

====

comments = from p in _db.Master

join t in _db.Details on p.DetailID equals t.DetailID into tg

select new 
{

 A = p.Column1,

//this next column is the one from the left joined table

 B = tg.FirstOrDefault(t => t.DetailID == p.DetailID).Column2

};

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