//数据库连接类
            SqlConnection conn = new SqlConnection("server=.;database=test;user=sa;pwd=123456");
            
            //创建操作对象
            SqlCommand cmd = conn.CreateCommand();
            //操作语句
            cmd.CommandText = "select * from Student";
            //打开数据库连接
            conn.Open();
            //执行读取操作
            SqlDataReader dr = cmd.ExecuteReader();
            //操作dr，利用sqldatareader中的读取方法来一行行读取数据
            while (dr.Read())
            {
                Console.Write(dr[0].ToString() + "    ");
                Console.Write(dr[1].ToString() + "    ");
                Console.Write(dr["Sname"].ToString() + "    \n");
            }
            //记得用完关闭数据库
            conn.Close();