SqlDataReader读取数据

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


namespace ConsoleApplication11
{
    class Program
    {
        static void Main(string[] args)
        {
            SqlConnection conn = new SqlConnection("Server=zhuobin;uid=sa;pwd=zhuobin;database=northwind");
            string sql = @"select contactname from customers";
            try
            {
                conn.Open();
                //create the command
                SqlCommand cmd = new SqlCommand(sql,conn);
                SqlDataReader reader = cmd.ExecuteReader();
                while (reader.Read())
                {
                    Console.WriteLine("{0}",reader[0]);
                } reader.Close();

            }
            catch (SqlException ex)
            {
                Console.WriteLine("The error:" + ex.Message);
            }
            finally
            {
                conn.Close();
                Console.WriteLine("The end!");
            }
            Console.ReadLine();
            

        }
    }
}