Linq left join 怎么写？？？求正解！

2010-08-12 02:00:00 794 阅读 AI 写同款 · GEO 优化AI 选题数据监测一键分发 ›

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要求分别实现类似以下两种情况的 Linq 语句

谢谢！

select * 

from table1

left join table2 on table1.Id = table2.empId

left join table3 on table2.deptId = table3.deptId

where table1.id > 10

select * 

from table1

left join table2 on table1.Id = table2.empId

left join table3 on table1.deptId = table3.deptId

where table1.id > 10

...全文

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切换为时间正序

Jueyoung 2010-08-12

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LINQ to Entities does not recognize the method , and this method cannot be translated into a store expression.

为什么啊？？？

Jueyoung 2010-08-12

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[Quote=引用 6 楼 q107770540 的回复:]

C# code

//1 .
DbContext db=new DbContext ();
var q=from t1 in db.Table1
join t2 in db.Table2
on t1.Id equals t2.empId
join t3 in db.Table3
……
[/Quote]

这样貌似就是 inner join 了呀

Jueyoung 2010-08-12

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谢谢各位我要逐一再试一试

wuyq11 2010-08-12

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var q =
from e in db.Employees
join o in db.Books on e.EmployeeID equals o.EmployeeID into b
from x in b.DefaultIfEmpty()
select new
{
e.ID,
e.Name,
o.BookName
};

q107770540 2010-08-12

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//1 .

  DbContext db=new DbContext ();

        var q=from t1 in db.Table1

              join t2 in db.Table2

              on t1.Id equals t2.empId 

              join t3 in db.Table3

              on t2.deptId equals t3.detpId

              where t1.id>10

              select new {t1.id,t1......}





//2



  DbContext db=new DbContext ();

        var q=from t1 in db.Table1

              join t2 in db.Table2

              on t1.Id equals t2.empId 

              join t3 in db.Table3

              on t1.deptId equals t3.detpId

              where t1.id>10

              select new {t1.id,t1......}

q107770540 2010-08-12

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使用DefaultIfEmpty 翻译成SQL语句不是LEFT JOIN，而是LEFT OUT JOIN

醉爱 2010-08-12

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你先看看tb里面有没有值

Jueyoung 2010-08-12

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但是这样写我用 tb.FirstOrDefault() 就出错呢？

醉爱 2010-08-12

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1)
var tb = from tb1 in table1
join tb2 in table2 on tb1.Id equals tb2.empId into ggg
from gg in ggg.DefaultIfEmpty()
join tb3 in table3 on gg.deptId equals tb3.deptId into kkk
from kk in kkk.DefaultIfEmpty()
where (tb1.Id > 10)
select new
{
tb1.id
...
kk.deptId
...
};
2)
var tb = from tb1 in table1
join tb2 in table2 on tb1.Id equals tb2.empId into ggg
from gg in ggg.DefaultIfEmpty()
join tb3 in table3 on tb1.deptId equals tb3.deptId into kkk
from kk in kkk.DefaultIfEmpty()
where (tb1.Id > 10)
select new
{
tb1.id
...
kk.deptId
...
};

Jueyoung 2010-08-12

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么有人呢？

Linq left join 怎么写？？？ 求正解！

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Linq left join 怎么写？？？求正解！