private void set_initial_form_load()
{
load_data_2_sle_chon_nv();
load_data_2_sle_loai_thu_nhap();
load_data_2_sle_cach_tinh_thue();
m_txt_chon_thang.Text = DateTime.Now.Month.ToString();
m_txt_chon_nam.Text = DateTime.Now.Year.ToString();
m_txt_so_tien.Text = "0";
}