private void btnExcel_Click(object sender, EventArgs e)
        {
            SaveFileDialog dlg = new SaveFileDialog();

            if (dlg.ShowDialog() == DialogResult.OK)
            {
                string  fileName = Path.Combine(Path.GetDirectoryName(Application.ExecutablePath), "テーブル定義書.xls");
                NCExcel execel   = new NCExcel();
                execel.OpenExcelFile(fileName);
                execel.SelectSheet(1);
                int idx = 7;
                // add table list
                foreach (Tbl tbl in tables)
                {
                    execel.setValue(2, idx, (idx - 6).ToString());
                    execel.setValue(4, idx, tbl.name);
                    idx++;
                }
                // add sheet
                execel.AddSheet(tables);
                // add sheet data
                for (int i = 0; i < tables.Count; i++)
                {
                    execel.SelectSheet(i + 2);
                    execel.setValue(2, 2, "HighwayHR");
                    execel.setValue(4, 2, "HRWeb");
                    execel.setValue(9, 2, "Highwayns");
                    execel.setValue(11, 2, DateTime.Now.ToString("yyyy/MM/dd"));
                    execel.setValue(2, 4, tables[i].name);
                    idx = 7;
                    for (int j = 0; j < tables[i].fields.Count; j++)
                    {
                        execel.setValue(2, idx, (idx - 6).ToString());
                        execel.setValue(3, idx, tables[i].fields[j]);
                        execel.setValue(4, idx, tables[i].fields_type[j]);
                        execel.setValue(5, idx, tables[i].fields_size[j].Replace("(", "").Replace(")", ""));
                        if (tables[i].fields_null[j] == "NOT NULL")
                        {
                            execel.setValue(7, idx, "○");
                        }
                        if (tables[i].pk.IndexOf(tables[i].fields[j]) > -1)
                        {
                            execel.setValue(8, idx, "○");
                        }
                        execel.setValue(9, idx,
                                        tables[i].fields_increase[j] + "/"
                                        + tables[i].fields_default[j] + "/"
                                        + tables[i].fields_sign[j]);
                        idx++;
                    }
                }
                execel.SaveAs(dlg.FileName);
                MessageBox.Show("Save Over!");
            }
        }