public void ShowT()
{
DataTable dt = new DataTable();
dt = Bus.GetListT("SELECT * FROM dbo.Thuoc WHERE TenThuoc NOT IN (SELECT TenThuoc FROM dbo.ChiTietHoaDonXuat INNER JOIN dbo.Thuoc ON Thuoc.MaThuoc = ChiTietHoaDonXuat.MaThuoc WHERE MaHDX='" + txt_MaHD.Text + "') AND TTT='0'");
cbTenThuoc.DataSource = dt;
cbTenThuoc.DisplayMember = "TenThuoc";
cbTenThuoc.ValueMember = "MaThuoc";
}