private void ExportToPDF()
        {
            connection.Open();
            string query = "SELECT card_index.name AS 'Nazwa produktu', card_index.unit AS 'Jedn.miar', card_index.price AS 'Cena jednostki', ROUND(SUB1.expense_total, 2) AS 'Ilosc', ROUND(SUB1.expense_total * card_index.price, 2) AS 'Wartosc', card_index.file AS 'Nr. kartoteki' FROM(SELECT T1.id_inventory, DATE_FORMAT(T1.date_add_inventory, '%d.%m.%Y') AS date_add_inventory, T1.id_ci_index, T1.id_invoice_index, SUM(T2.expenditure_inventory) AS expense_total FROM inventory T1, inventory T2 WHERE T1.date_add_inventory >= T2.date_add_inventory AND T1.id_inventory = T2.id_inventory GROUP BY T1.id_ci_index) SUB1 JOIN inventory ON SUB1.id_inventory = inventory.id_inventory INNER JOIN card_index ON inventory.id_ci_index = card_index.id ORDER BY NAME DESC;";
            MySqlCommand command = new MySqlCommand(query, connection);
            MySqlDataAdapter adapter = new MySqlDataAdapter(command);
            DataTable dataTable = new DataTable();
            adapter.Fill(dataTable);

            Document document = new Document();
            PdfWriter writer = PdfWriter.GetInstance(document, new FileStream(@"E:\OneDrive\Pulpit\test1.pdf", FileMode.Create));
            document.Open();

            PdfPTable table = new PdfPTable(dataTable.Columns.Count);
            table.WidthPercentage = 100;

            for (int k = 0; k < dataTable.Columns.Count; k++)
            {
                PdfPCell cell = new PdfPCell(new Phrase(dataTable.Columns[k].ColumnName));

                cell.HorizontalAlignment = PdfPCell.ALIGN_CENTER;
                cell.VerticalAlignment = PdfPCell.ALIGN_CENTER;
                cell.BackgroundColor = new iTextSharp.text.BaseColor(192, 192, 192);

                table.AddCell(cell);
            }

            for (int i = 0; i < dataTable.Rows.Count; i++)
            {
                for (int j = 0; j < dataTable.Columns.Count; j++)
                {
                    PdfPCell cell = new PdfPCell(new Phrase(dataTable.Rows[i][j].ToString()));

                    cell.HorizontalAlignment = PdfPCell.ALIGN_CENTER;
                    cell.VerticalAlignment = PdfPCell.ALIGN_CENTER;

                    table.AddCell(cell);
                }
            }
            document.Add(table);
            document.Close();
            connection.Close();
        }