NPOI 使用 2.1.1 版
礙於難以言喻的限制
無法把 NPOI 更新到最新版本

使用 .xlsx 檔，當表格範本使用
可是
sheet.CopyRow(sourceIndex, targetIndex);
沒辦法用?
沒錯誤訊息，但是 targetIndex 的Row 抓到都是 null?

換個方向想，也許是舊版的NPOI有缺陷?
找個 .xls 檔用的 CopyRow 來改寫

出處： https://dotblogs.com.tw/kim66766/2011/04/09/npoi-copy-row
改寫成

    private void ExcelCopyRow(IWorkbook workbook, ISheet worksheet, int sourceRowNum, int destinationRowNum)
    {
        // Get the source / new row
        IRow newRow = worksheet.GetRow(destinationRowNum);
        IRow sourceRow = worksheet.GetRow(sourceRowNum);

        // If the row exist in destination, push down all rows by 1 else create a new row
        if (newRow != null)
        {
            worksheet.ShiftRows(destinationRowNum, worksheet.LastRowNum, 1);
        }
        else
        {
            newRow = worksheet.CreateRow(destinationRowNum);
        }

        // Loop through source columns to add to new row
        for (int i = 0; i < sourceRow.LastCellNum; i++)
        {
            // Grab a copy of the old/new cell
            ICell oldCell = sourceRow.GetCell(i);
            ICell newCell = newRow.CreateCell(i);

            // If the old cell is null jump to next cell
            if (oldCell == null)
            {
                newCell = null;
                continue;
            }

            // Copy style from old cell and apply to new cell
            ICellStyle newCellStyle = workbook.CreateCellStyle();
            newCellStyle.CloneStyleFrom(oldCell.CellStyle); ;
            newCell.CellStyle = newCellStyle;

            // If there is a cell comment, copy
            if (newCell.CellComment != null) newCell.CellComment = oldCell.CellComment;

            // If there is a cell hyperlink, copy
            if (oldCell.Hyperlink != null) newCell.Hyperlink = oldCell.Hyperlink;

            // Set the cell data type
            newCell.SetCellType(oldCell.CellType);

            // Set the cell data value
            switch (oldCell.CellType)
            {
                case CellType.Blank:
                    newCell.SetCellValue(oldCell.StringCellValue);
                    break;
                case CellType.Boolean:
                    newCell.SetCellValue(oldCell.BooleanCellValue);
                    break;
                case CellType.Error:
                    newCell.SetCellErrorValue(oldCell.ErrorCellValue);
                    break;
                case CellType.Formula:
                    newCell.SetCellFormula(oldCell.CellFormula);
                    break;
                case CellType.Numeric:
                    newCell.SetCellValue(oldCell.NumericCellValue);
                    break;
                case CellType.String:
                    newCell.SetCellValue(oldCell.RichStringCellValue);
                    break;
                case CellType.Unknown:
                    newCell.SetCellValue(oldCell.StringCellValue);
                    break;
            }
        }

        // If there are are any merged regions in the source row, copy to new row
        for (int i = 0; i < worksheet.NumMergedRegions; i++)
        {
            CellRangeAddress cellRangeAddress = worksheet.GetMergedRegion(i);
            if (cellRangeAddress.FirstRow == sourceRow.RowNum)
            {
                CellRangeAddress newCellRangeAddress = new CellRangeAddress(newRow.RowNum,
                                                                            (newRow.RowNum +
                                                                             (cellRangeAddress.FirstRow -
                                                                              cellRangeAddress.LastRow)),
                                                                            cellRangeAddress.FirstColumn,
                                                                            cellRangeAddress.LastColumn);
                worksheet.AddMergedRegion(newCellRangeAddress);
            }
        }

    }
    

結果還是一樣?
Row 抓到 0 ~ 30 的
31以後通通都是null
沒複製到? 有人遇過同樣的問題嗎?
想了4天了，找不出來問題出在哪裡？