c#访问数据库

using System;
using System.Collections.Generic;
using System.Text;
using System.Data.Common;
using System.Data.SqlClient;
//using System.Data.SqlTypes;

namespace database
{
    class Program
    {
        static void Main(string[] args)
        {           
            string source = "server=(local);" + "Integrated Security=true;"+"database=图书借阅";       
            //连接串,本地windows身份登陆sql,连接数据库图书借阅
            string select = "SELECT * FROM book";
            //查询语句
            SqlConnection  conn = new SqlConnection(source);
            //连接对象
            SqlCommand cmd = new SqlCommand(select, conn);
            //Sql命令
           
            conn.Open();         

            //--------读取数据-------------
            SqlDataReader reader = cmd.ExecuteReader();                    
            while (reader.Read())
            {
                Console.WriteLine("{0}  {1}  {2}  {3}  {4}  {5}", reader[0].ToString().Trim(), reader[1].ToString().Trim(), reader[2].ToString().Trim(), reader[3].ToString().Trim(), reader[4].ToString().Trim(), reader[5].ToString().Trim());
            }
            //--------.Trim()方法用于去掉字符串两边的空格
           
            conn.Close();   //☆

            //---------返回记录个数---------------------
            string select2 = "SELECT COUNT(*) FROM book";
            SqlCommand  cmd2 =new SqlCommand(select2, conn);
                    //由此行可见conn对象还没有被撤消
            conn.Open();
            object o = cmd2.ExecuteScalar();
            Console.WriteLine(o.ToString());
           
            conn.Close();
            conn.Dispose();
            conn = null;
            //执行以上两行后conn对象才被撤消。

            //此外，.open()和.close()之间，的代码越少，越节省资源。

        }
    }
}
//图书借阅数据库中有表book, book表有6个属性列