private void btnshow_Click(object sender, EventArgs e)
        {
            try
            {
                int             i = data_mail.CurrentRow.Index;
                DataGridViewRow a = data_mail.Rows[i];
                string          sid;
                string          sname;
                string          sidchannel;
                string          smail;
                string          sga;
                string          snote;

                // gán giá ntri5
                sid = a.Cells["id"].Value.ToString();

                sname      = a.Cells["Name"].Value.ToString();
                sidchannel = a.Cells["idchannel"].Value.ToString();
                smail      = a.Cells["mail"].Value.ToString();
                sga        = a.Cells["ga"].Value.ToString();
                snote      = a.Cells["note"].Value.ToString();

                Addnew show = new Addnew(sid, sname, sidchannel, smail, sga, snote, 2);

                show.ShowDialog();
            }
            catch
            {
            }
        }
        private void btnthem_Click(object sender, EventArgs e)
        {
            int c = layso();

            c++;
            Addnew a = new Addnew(c, 1);

            a.ShowDialog();
            if (!string.IsNullOrEmpty(id))
            {
                DataRow r = dataset.Tables["data_trial"].NewRow();
                r["id"]        = id;
                r["Name"]      = name;
                r["idchannel"] = idchannel;
                r["mail"]      = mail;
                r["ga"]        = ga;
                r["note"]      = note;
                dataset.Tables["data_trial"].Rows.Add(r);
                MessageBox.Show("ok");
            }
            // khởi tạo về ban đầu
            id        = string.Empty;
            name      = string.Empty;
            idchannel = string.Empty;
            ga        = string.Empty;
            note      = string.Empty;
            mail      = string.Empty;
        }