protected void btn_submit_Click(object sender, EventArgs e)
    {
        bool isLegal = bl.is_legal_student(txt_enroll_no.Text, txt_fn.Text, txt_ln.Text, Convert.ToInt32(drp_clg.SelectedValue), txt_mob_no.Text, txt_email.Text);

        if (isLegal)
        {
            int i = bl.insert_student(txt_enroll_no.Text, txt_fn.Text, txt_ln.Text, Convert.ToInt32(drp_city.SelectedValue), Convert.ToInt32(drp_clg.SelectedValue), txt_dept.Text, txt_sem.Text, Convert.ToInt32(drp_country_code.SelectedValue), txt_mob_no.Text, rb_gender.SelectedValue, txt_email.Text, txt_pswd.Text);
            if (i > 0)
            {
                Response.Redirect("stu_login.aspx");
            }
        }
        else
        {
            Response.Write("<script>alert('Please enter correct information')</script>");
        }
    }