private void frm_HoaDon_Load(object sender, EventArgs e)
{
load();
nghiepvu();
cb_NV.DataSource = null;
cb_NV.Items.Clear();
cb_NV.DataSource = nv.GetNhanViens();
cb_NV.ValueMember = "MaNV";
cb_NV.DisplayMember = "TenNV";
}
private void refress()
{
gridControl1.DataSource = nv.GetNhanViens();
}