2.3 IQueryable与 IEnumerable的区别

static void Main(string[] args)
        {
            //创建数据库访问网关
            using (SchoolDBEntities schoolEntities = new SchoolDBEntities())
            {
                //查询的结果放入IQueryable接口的集合中
                IQueryable classesIQue = (from c in schoolEntities.T_Class
                                                   orderby c.ID
                                                     select c).Skip(3).Take(3);
                //注意这个AsEnumerable()在分页查询之前，先将其转换成IEnumerable类型
                IEnumerable classesIEnu = (from c in schoolEntities.T_Class
                                                    orderby c.ID  
                                                    select c).AsEnumerable().Skip(3).Take(3);
                //因为启用了延迟加载机制，所以下面调用一下，才会真正去读取数据库
                int i = 0;
                foreach (var c in classesIQue)
                {
                    i++;
                }
                Console.WriteLine(i);
                foreach (var c in classesIEnu)
                {
                    i++;
                }
                Console.WriteLine(i);
            }
            Console.WriteLine("OK");
            Console.ReadKey();
        }