SqlHelper的使用与DataSet-SqlDataAdapter

try
            {
                string sUsername = TextUserName.Text.Trim();
                string sPwd = TextBoxPwd.Text.Trim();
                if(string.IsNullOrEmpty(sUsername) || string.IsNullOrEmpty(sPwd))
                {
                    Response.Write(@"<script>alert(""No Username or no Password..."");</script>");
                }
                else
                {
                    string sSql = "select count(*) from UserInfor where UserName=@UserName and Pwd=@Pwd";
                    SqlParameter[] paras = new SqlParameter[] {
                        new SqlParameter("@UserName",sUsername),
                        new SqlParameter("@Pwd",sPwd)
                        };
                    if(SqlHelper.Exists(sSql,paras))
                    {
                        Response.Redirect("UserM.aspx");
                    }
                    else
                    {
                        Response.Write(@"<script>alert(""Username or Password is Wrong! "");</script>");
                    }
                }
            }
            catch 
            {
                Response.Write(@"<script>alert(""The WebSite is under repairing..."");</script>");
            }

string connStr = ConfigurationManager.ConnectionStrings["sq_ruanmou"].ToString();
        DataSet ds = new DataSet();
        protected void Page_Load(object sender, EventArgs e)
        {
            SqlConnection con = new SqlConnection(connStr);
            string s = "select * from UserInfor";
            using (SqlCommand cmd = new SqlCommand(s, con))
            {
                SqlDataAdapter ad = new SqlDataAdapter(cmd);
                ad.Fill(ds);
                DataTable dt = ds.Tables[0];
                GridView1.DataSource = dt;
                GridView1.DataBind();
            }
        }