protected void LinkButton1_Click(object sender, EventArgs e)
    {
        Author author = new Author();

        if (author.CheckUser(txtID.Text))
        {
            Response.Write("<Script Language=JavaScript>alert(\"恭喜该用户名可用!\")</Script>");
        }
        else
        {
            Response.Write("<Script Language=JavaScript>alert(\"该用户名已注册!\")</Script>");
        }
    }