Can't write data to existing xlsx file

问题

I wrote this code below

            string filePath = @"C:\report_data.xlsx";

            // Saves the file via a FileInfo 
            var file = new FileInfo(filePath);

            // Creates the package and make sure you wrap it in a using statement
            using (var package = new ExcelPackage(file))
            {
                // Adds a new worksheet to the empty workbook
                OfficeOpenXml.ExcelWorksheet worksheet = package.Workbook.Worksheets.Add("Report System - " + DateTime.Now.ToShortDateString());

                // Starts to get data from database
                for (int row = 1; row < 10; row++)
                {
                    // Writes data from sql database to excel's columns
                    for (int col = 1; col < 10; col++)
                    {                            
                        worksheet.Cells[row, col].Value = row * col;
                    }// Ends writing data from sql database to excel's columns

                }// Ends getting data from database


                // Saves new workbook and we are done!
                package.Save();
            }

When i opened the file , it had nothing and the page was blank. But when i saw the file size , it increased . Why was the page blank while the file size increased and how can i write data to it ?

Remark : When i tried deleting the existing file and run a program, the program generated the file and the file had values displayed in the columns . On the other hand , i tried creating file first and then run the program and the result was blank like i said above .

回答1:

I found out the answer . I just changed the line at

OfficeOpenXml.ExcelWorksheet worksheet = 
  package.Workbook.Worksheets.Add("Report System - " +
    DateTime.Now.ToShortDateString());

OfficeOpenXml.ExcelWorksheet worksheet = 
  package.Workbook.Worksheets["Sheet1"];

and it worked !!.

Because Sheet1 is the default name of worksheet and it existed in my file at line:

string filePath = @"C:\report_data.xlsx";

Actually, in this case, package.Workbook.Worksheets.Add means to add the worksheet's name and I found that it didn't have to add the worksheet's name because it already exists.

来源：https://stackoverflow.com/questions/17486391/cant-write-data-to-existing-xlsx-file

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