使用Open Xml向现有Excel 2007工作簿添加列

我有一个预定义的Excel工作簿，所有的工作表在适当的地方，我需要写内容到它。我成功地给细胞写信。

问题是在一个特定的工作表，我需要添加三列到它。在下面的代码中，首先我抓住Worksheet，然后我继续添加列。这段代码运行得很好，我的意思是，没有抛出异常，但是当我试图打开Excel文件时，我得到一个错误，说明有一些内容无法读取，并且此特定工作表的所有内容都被清除。

我知道问题在于此操作，因为如果我注释掉那些添加列的行，工作簿将与我从代码中编写的所有单元格值一起打开。

这是相关的代码，为了测试的目的，我试图添加3列:

using (SpreadsheetDocument document = SpreadsheetDocument.Open(outputPath, true)){
        Sheet sheet2 = document.WorkbookPart.Workbook.Descendants<Sheet>().Single( s => s.Name == "Miscellaneous Credit" );
        Worksheet workSheet2 = ( (WorksheetPart)document.WorkbookPart.GetPartById( sheet2.Id ) ).Worksheet;
        Columns cs = new Columns();
        for ( var y = 1; y <= 3; y++ ) {                    
            Column c = new Column()
            {
                Min = (UInt32Value)1U,
                Max = (UInt32Value)1U,
                Width = 44.33203125D,
                CustomWidth = true
            };
            cs.Append( c );
        }
        workSheet2.Append( cs );
    }

编辑:根据Chris对列概念的解释

using (SpreadsheetDocument document = SpreadsheetDocument.Open(outputPath, true)){
        Sheet sheet2 = document.WorkbookPart.Workbook.Descendants<Sheet>().Single( s => s.Name == "Miscellaneous Credit" );
        Worksheet workSheet2 = ( (WorksheetPart)document.WorkbookPart.GetPartById( sheet2.Id ) ).Worksheet;
       // Check if the column collection exists
            Columns cs = workSheet2.Elements<Columns>().FirstOrDefault();
            if ( ( cs == null ) ) {
                // If Columns appended to worksheet after sheetdata Excel will throw an error.
                SheetData sd = workSheet2.Elements<SheetData>().FirstOrDefault();
                if ( ( sd != null ) ) {
                    cs = workSheet2.InsertBefore( new Columns(), sd );
                }
                else {
                    cs = new Columns();
                    workSheet2.Append( cs );
                }
            }
            //create a column object to define the width of columns 1 to 3  
            Column c = new Column
            {
                Min = (UInt32Value)1U,
                Max = (UInt32Value)3U,
                Width = 44.33203125,
                CustomWidth = true
            };
            cs.Append( c );
    }

using (SpreadsheetDocument document = SpreadsheetDocument.Open(outputPath, true)) {
    Sheet sheet2 = document.WorkbookPart.Workbook.Descendants<Sheet>().Single(s => s.Name == "Your sheet name");
    Worksheet workSheet2 = ((WorksheetPart)document.WorkbookPart.GetPartById(sheet2.Id)).Worksheet;
    // Check if the column collection exists
    Columns cs = workSheet2.Elements<Columns>().FirstOrDefault();
    if ((cs == null)) {
        // If Columns appended to worksheet after sheetdata Excel will throw an error.
        SheetData sd = workSheet2.Elements<SheetData>().FirstOrDefault();
        if ((sd != null)) {
            cs = workSheet2.InsertBefore(new Columns(), sd);
        } else {
            cs = new Columns();
            workSheet2.Append(cs);
        }
    }
    //create a column object to define the width of columns 1 to 3  
    Column c = new Column {
        Min = (UInt32Value)1U,
        Max = (UInt32Value)3U,
        Width = 44.33203125,
        CustomWidth = true
    };
    cs.Append(c);
}