private void txtTimKiem_HoTen_TextChanged(object sender, EventArgs e)
 {
     if (txtTimKiem_HoTen.Text != "")
     {
         dt = tk.Tim_NV(txtTimKiem_HoTen.Text);
         lsvTaiKhoan.Items.Clear();
         lsvTaiKhoan.View = View.Details;
         for (int i = 0; i < dt.Rows.Count; i++)
         {
             ListViewItem lvi;
             lvi = lsvTaiKhoan.Items.Add(dt.Rows[i]["TenTK"].ToString());
             lvi.SubItems.Add(dt.Rows[i][1].ToString());
             lvi.SubItems.Add(dt.Rows[i][2].ToString());
             lvi.SubItems.Add(dt.Rows[i][3].ToString());
         }
         if (lsvTaiKhoan.Items.Count > 0)
         {
             lsvTaiKhoan.Items[0].Selected  = true;
             lsvTaiKhoan.Items[0].ForeColor = Color.RoyalBlue;
         }
     }
     else
     {
         LayDS_TaiKhoan();
         ClearForm();
         if (lsvTaiKhoan.Items.Count > 0)
         {
             lsvTaiKhoan.Items[0].ForeColor = Color.Black;
         }
     }
 }