asp.net登录及注册页面代码实现

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
public partial class Login : System.Web.UI.Page
{
    protected System.Data.SqlClient.SqlConnection Cn;
    protected System.Data.SqlClient.SqlCommand Cm;
    protected System.Data.SqlClient.SqlDataAdapter Da;
    protected System.Data.DataSet Ds;
    protected System.Data.SqlClient.SqlDataReader Dr;
    protected void Page_Load(object sender, EventArgs e)
    {
        //if (Session["username"] == null || Session["username"] == "") //上面Session名字用LoginUser,这里的名字要和上面的相同,可以随便改,保持一致就行了,注意:Session ["LoginUser"]后面,没有ToString()哦,你要是加上的话,就会出错了.
        //{
        //    Response.Redirect("Login.Aspx"); //如果Session为空,则转到登陆页.
        //}
    }
    protected void Regist_Click(object sender, EventArgs e)
    {
        string str = ConfigurationSettings.AppSettings["strConnection"];
        Cn = new SqlConnection(str);
        Cn.Open();