C#中用session实现的用户登录代码与退出登录代码

点击登录按钮Button时

protected void denglu_Click(object sender, EventArgs e)
    {
        SqlConnection cn = conn.CreateConnection();
        SqlCommand com = new SqlCommand();
        com.Connection = cn;
        cn.Open();
        com.CommandText = "select count(*) from [Members] where [UserName]='" + this.username.Text + "' and [Password]='"+this.password.Text+"'";//数据库中username每个用户的都不一样，确定是否符合用户要求
        int a = Convert.ToInt32(com.ExecuteScalar());
        if (a>0)
        {
            Session["UserName"] = this.username.Text;
            Session["PassWord"] = this.password.Text;
            Response.Write("");
            //Panel1.Visible = false;//登录框界面
            //Panel2.Visible = true;//登录后界面
        }
        else
        {
            Response.Write("");
        }
        cn.Close();
    }

点击退出登录的LinkButton时

protected void LinkButton3_Click(object sender, EventArgs e)
    {
        Session.Abandon();
        Session.Clear();
        Response.Redirect("~/Default.aspx");
    }