C# DataReader

            //1   连接字符串
            string connectionString
                = "server=127.0.0.1;integrated security=true;database=MSPetShop4";
            // = "server=.;uid=sa;pwd=SQL@5;database=AdventureWorks2012";
            // = "server=.;user id=sa;password=SQL@5;database=AdventureWorks2012";
            //2 实例化数据库连接
            using(System.Data.SqlClient.SqlConnection connection = new SqlConnection(connectionString))
            {
                string sql = "SELECT 客户,产品,数量 FROM dbo.A";
                connection.Open();
                System.Data.SqlClient.SqlCommand command = new SqlCommand(sql, connection);
                //通过数据库中的游标来辅助读取查询结果.
                System.Data.SqlClient.SqlDataReader reader = command.ExecuteReader();

                //DataReader 通过方法Read 来读取一行记录,Read方法返回结果为bool.DataReader 会自动进一取数据.
                //读取到的数据保存在DataReader对象内
                while(reader.Read())
                {
                    //通过
                    string kh = reader.GetString(0);
                    string cp = reader.GetString(1);
                    int sl = reader.GetInt32(2);
                    Console.WriteLine(kh + "," + cp + "," + sl);
                }

                //DataReader读取之后游标也需要关闭
                reader.Dispose();
            }
            Console.ReadLine();