下面以linq to sql的实例介绍 not in 查询和 in查询，linq的用法类似。

　　一、T-SQL的IN

Select ProductID, ProductName, CategoryID
From dbo.Products
Where CategoryID in (1, 2)

　　二、LINQ to SQL 实现IN

var queryResult = from p in db.Products
where (new int[] {1,2}).Contains(p.CategoryID)
select p;

　　三、T-SQL的NOT IN

Select ProductID, ProductName, CategoryID
From dbo.Products
Where CategoryID not in (1, 2)

　　四、LINQ to SQL 实现 NOT IN

var queryResult = from p in db.Products
where !(new int[] {1,2}).Contains(p.CategoryID)
select p;

　　五、LINQ to SQL 实现 NOT IN子查询

from a in TableA where !(from b in TableB Where ... select b.Id).Contains(a.Id)

　　六、Linq 实现方式

//比如 Id in (1,2,3)
int[] a={1,2,3};
list.Where(x=>a.Contains(x.Id))