你怎么能处理与LINQ to SQL的IN子查询？

我有点卡在这个。 基本上我想要做一些像LINQ to SQL中的以下SQL查询：

SELECT f.* FROM Foo f WHERE f.FooId IN ( SELECT fb.FooId FROM FooBar fb WHERE fb.BarId = 1000 ) 

任何帮助将受到感谢。

谢谢。

Answer 1

看看这篇文章 。 基本上，如果你想得到相当于IN，你需要先构造一个内部查询，然后使用Contains（）方法。 这是我翻译的尝试：

 var innerQuery = from fb in FoorBar where fb.BarId = 1000 select fb.FooId; var result = from f in Foo where innerQuery.Contains(f.FooId) select f; 

Answer 2

在LINQ to SQL中实现IN的一般方法

 var q = from t1 in table1 let t2s = from t2 in table2 where <Conditions for table2> select t2.KeyField where t2s.Contains(t1.KeyField) select t1; 

在LINQ to SQL中实现EXISTS的一般方法

 var q = from t1 in table1 let t2s = from t2 in table2 where <Conditions for table2> select t2.KeyField where t2s.Any(t1.KeyField) select t1; 

Answer 3

 from f in Foo where f.FooID == ( FROM fb in FooBar WHERE fb.BarID == 1000 select fb.FooID ) select f; 

Answer 4

尝试使用两个单独的步骤：

 // create a Dictionary / Set / Collection fids first var fids = (from fb in FooBar where fb.BarID = 1000 select new { fooID = fb.FooID, barID = fb.BarID }) .ToDictionary(x => x.fooID, x => x.barID); from f in Foo where fids.HasKey(f.FooId) select f 

Answer 5

//先创build一个Dictionary / Set / Collection fids

查找其他Artilces

 var fids = (from fb in FooBar where fb.BarID = 1000 select new { fooID = fb.FooID, barID = fb.BarID }) .ToDictionary(x => x.fooID, x => x.barID); from f in Foo where fids.HasKey(f.FooId) select f 

Answer 6

尝试这个

 var fooids = from fb in foobar where fb.BarId=1000 select fb.fooID var ff = from f in foo where f.FooID = fooids select f 

Answer 7

 var foos = Foo.Where<br> ( f => FooBar.Where(fb.BarId == 1000).Select(fb => fb.FooId).Contains(f.FooId)); 

Answer 8

 from f in foo where f.FooID equals model.FooBar.SingleOrDefault(fBar => fBar.barID = 1000).FooID select new { f.Columns }; 

Answer 9

//先创build一个Dictionary / Set / Collection fids

查找其他Artilces

 var fids = (from fb in FooBar where fb.BarID = 1000 select new { fooID = fb.FooID, barID = fb.BarID }) .ToDictionary(x => x.fooID, x => x.barID); from f in Foo where fids.HasKey(f.FooId) select f