数据访问类的定义

//从配置文件中获取连接字符串
            string connstr = WebConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;

            //创建连接对象
            OleDbConnection conn = new OleDbConnection(connstr);

            string sqlText = "select * from students where StuName='" + txtName.Text + "' and StuPwd='" + txtPwd.Text+"'";

            //创建命令对象
            OleDbCommand cmd = new OleDbCommand( sqlText, conn);

            //打开数据库连接
            conn.Open();

            //执行命令对象中的sql命令，获取数据
            //注意datareader的特点，只读，向前，每次一条记录。
            OleDbDataReader dr = cmd.ExecuteReader();

            if (dr.Read())
            {
                lblMessage.Text = "登录成功";
                Session["IsLogin"] = true;
              Session["StudentID"]= dr["StuID"].ToString();

            }
            else lblMessage.Text = "登录失败";

            dr.Close();
            conn.Close();