private void button23_Click(object sender, EventArgs e)
        {
            //get data from databse tab
            t.timeday = Convert.ToInt32(timeday.Text);
            bool success = t.Delete(t);

            if (success == true)
            {
                MessageBox.Show("Success to delete this week");
                //refreash
                DataTable dt = t.Select();
                daytimeview.DataSource = dt;
            }
            else
            {
                MessageBox.Show("Failed delete");
            }
        }