private void cmbloaikh1_SelectedIndexChanged(object sender, EventArgs e)
{
if (ck == 0)
{
txtthongkeloaikh.Text = tkBLL.Thongke_theoLoaiKH(int.Parse(cmbloaikh1.SelectedValue.ToString())).ToString();
tkBLL.Hienthi_TKLoaiKH(lvthongkeloaikh, int.Parse(cmbloaikh1.SelectedValue.ToString()));
}
if (ck == 1)
{
txtthongkeloaikh.Text = tkBLL.Thongke_theoLoaiKH(1).ToString();
tkBLL.Hienthi_TKLoaiKH(lvthongkeloaikh, 1);
}
}