//Nút thêm
 private void pic_Them_Click(object sender, EventArgs e)
 {
     try
     {
         frm_AddCustomer addfrm = new frm_AddCustomer();
         addfrm.ShowDialog();
         LoadData("");
     }
     catch (Exception ex)
     {
         MessageBox.Show(ex.Message);
     }
 }
 //Nút sửa
 private void pic_Sua_Click(object sender, EventArgs e)
 {
     try
     {
         frm_AddCustomer suakhachhang = new frm_AddCustomer(this.kh);
         pn_Nav.Visible = false;
         suakhachhang.ShowDialog();
     }
     catch (Exception ex)
     {
         MessageBox.Show(ex.Message);
     }
 }