private void BtnExport_Click(object sender, EventArgs e) { ExportToExcel excel = new ExportToExcel(); string query = "SELECT * FROM dbo.HoaDonNhap"; System.Data.DataTable data = DataProvider.Instance.ExecuteQuery(query); excel.ExportHoaDonNhap(data, "Danh sach HDN", "DANH SÁCH HÓA ĐƠN NHẬP"); }