数据库连接 执行 select 语句

using System;
using System.Data.SqlClient;

namespace ConnectDB
{
    class Program
    {
        static void Main(string[] args)
        {
            //指定数据库连接的SqlConnection.ConnectionString性质
            //SqlConnection.ConnectionString详细详细参考
            //MSDN网站：http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlconnection.connectionstring.aspx
            string strConn = @"  server = (local); 
                                 integrated security = true;
                                 database = 'northwind'  ";
            /*
             * 另一种指定数据库连接的SqlConnection.ConnectionString性质的方法是
             * 使用SqlConnectionStringBuilder Class，
             * 代码例子如下，
             * 具体参考MSDN网站：http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlconnectionstringbuilder.aspx
             * 和网站：http://blogs.msdn.com/b/cbowen/archive/2007/03/05/sqlconnectionstringbuilder.aspx
                System.Data.SqlClient.SqlConnectionStringBuilder builder =
                                    new System.Data.SqlClient.SqlConnectionStringBuilder();
                builder["Data Source"] = "(local)";
                builder["integrated Security"] = true;
                builder["Initial Catalog"] = "AdventureWorks;NewValue=Bad";
                //SqlConnectionStringBuilder.ConnectionString作为参数用创建连接实例
                conn = new SqlConnection(builder.ConnectionString);
             */


            SqlConnection conn = null;
            SqlDataReader sqlReader = null;
            try
            {
                //用strConn创建连接
                conn = new SqlConnection(strConn);

                conn.Open();//打开连接

                //通过SqlConnection.CreateCommand()函数
                //创建数据库命令SqlCommand
                //SqlCommand的MSDN参考网站
                //http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlcommand.aspx
                SqlCommand sqlCmd = conn.CreateCommand();

                //SqlCommand.CommandText指定数据库查询命令
                sqlCmd.CommandText = "select * from dbo.Contacts";
                //执行数据库查询命令，并把结果返回给SqlDataReader对象。
                sqlReader = sqlCmd.ExecuteReader();
                //通过while循环SqlDataReader.Read(),遍历读取的结果。
                while (sqlReader.Read())
                {
                    Console.WriteLine("{0},{1}",
                        sqlReader["ContactType"].ToString().PadRight(10),
                        sqlReader["CompanyName"].ToString().PadRight(15));
                }
            }
            catch (Exception exp)
            {
                Console.WriteLine(exp.ToString());
            }
            finally
            {
                //别忘了要关闭连接哦！！
                sqlReader.Close();
                conn.Close();
            }
        }
    }
}