private void LoginButton_Click(object sender,System.EventArgs e)
{
        String sql=String.Format("select password from Administrator where AdminID='{0}',UseridBox.Text);
        SqlConnection conn=new SqlConnection(ConfigurationSettings.AppSettings["connectionString"]);
        SqlDataReader myreader=new SqlCommand(sql,conn).ExecuteReader();
        if(myreader.Read())
        {
                String hashed=FormsAuthentication.HashPasswordForStoringInConfigFile(PasswordTextBox.Text,"SHA1");
                //将用户输入的密码哈希后再与数据库是的哈希值进行比较
                if(hash==myreader["password"]).ToString())
                {
                        FormsAuthentication.RedirectFromLoginPage(UseridBox.Text,true);//转到请求页
                }
                else
                        Result.Text="密码错误";
        }
        else
                Result.Text="用户不存在";
        conn.Close();
}