如何在LINQ中使用letf外连接 [英] how to use letf outer join in LINQ

问题描述

var query=
                from _t in db.E_Cat
                join _s in db.E_StoryDetail on _t.CatID equals _s.SCat into testSubject
                      from _s in testSubject.DefaultIfEmpty()
                    group _t by new {_t.CatID,_t.CatName} into g
                select new { CatID = g.Key.CatID, CatName=g.Key.CatName, count = g.Count() };

推荐答案

var query = from _t in db.E_Cat

_s in db.E_StoryDe​​tail

on _t .CatID等于_s.SCat到testSubject

来自x in testSubject.DefaultIfEmpty（）

选择新的{

CatID = _t.CatID，CatName = _t.CatName，count = testSubject.Count（）};

var query = from _t in db.E_Cat
_s in db.E_StoryDetail
on _t .CatID equals _s.SCat into testSubject
from x in testSubject.DefaultIfEmpty()
select new {
CatID = _t.CatID, CatName=_t.CatName,count = testSubject.Count() };

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