using System;
using System.Collections.Generic;
using System.Data.Linq;
using System.Linq;
using System.Text;


namespace BegVCSharp_27_1_FirstLINQtoSQLquery
{
    class Program
    {
        static void Main(string[] args)
        {
            NorthwindDataContext NorthwindDataContext = new NorthwindDataContext();
            var queryresults = from c in NorthwindDataContext.customers
                              where c.country = "USA"
                              select new
                              {
                                  ID = c.customerID,
                                  Name = ,
                                  City = c.city,
                                  state = c.regin
                              };
            foreach (var item in queryresults)
            {
                Console.WriteLine(item);
            };
            Console.WriteLine("press enter/return to continue ...");
            Console.ReadKey();
        }
    }
}
Error    1    The type or namespace name 'NorthwindDataContext' could not be found (are you missing a using directive or an assembly reference?)    C:\Users\dell\AppData\Local\Temporary Projects\ConsoleApplication1\Program.cs    15    13    ConsoleApplication1
Error    2    The type or namespace name 'NorthwindDataContext' could not be found (are you missing a using directive or an assembly reference?)    C:\Users\dell\AppData\Local\Temporary Projects\ConsoleApplication1\Program.cs    15    61    ConsoleApplication1

你这个好像是LINQ to SQL查询，需要安装Northwind示例数据。要将Northwind数据库添加LINQ to SQL映射类。具体的看Csharp入门经典（第四版），有章节详细介绍。

System.Data.Linq;
注意添加dll的引用.

是不是空格多了，应该是空一行吧

找不到实体类NorthwindDataContext，添加一个这个

然后把数据表拖进设计器，有必要再改写代码，保存，引用包含这个类的库或页面就o了

[ 本帖最后由 mmxo 于 2012-11-14 20:40 编辑 ]