Can't sort excel worksheet using C#

Question

I want to programmatically sort an excel worksheet using C# but the code I used doesn't work:

        //the largest size of sheet in Excel 2010
        int maxRowAmount = 1048576;
        int maxColAmount = 16384;

        //Sort by the value in column G1
        sourceWorkSheet.Sort.SortFields.Add(sourceWorkSheet.Range["J:J"], XlSortOn.xlSortOnValues, XlSortOrder.xlAscending, XlSortDataOption.xlSortNormal);

        //Find out the last used row and column, then set the range to sort,
        //the range is from cell[2,1](top left) to the bottom right corner
        int lastUsedRow=sourceWorkSheet.Cells[maxRowAmount, 1].End[XlDirection.xlUp].Row;
        int lastUsedColumn=sourceWorkSheet.Cells[2, maxColAmount].End[XlDirection.xlToLeft].Column;
        Range r = sourceWorkSheet.Range[sourceWorkSheet.Cells[2, 1], sourceWorkSheet.Cells[lastUsedRow,lastUsedColumn ]];
        sourceWorkSheet.Sort.SetRange(r);

        //Sort!
        sourceWorkSheet.Sort.Apply();

I debug it using the messagebox to print of the value in the column "J" and the result is not sorted:

        //print out the sorted result
        Range firstColumn = sourceWorkSheet.UsedRange.Columns[10];
        System.Array myvalues = (System.Array)firstColumn.Cells.Value;
        string[] cmItem = myvalues.OfType<object>().Select(o => o.ToString()).ToArray();
        String msg="";
        for (int i = 0; i < 30; i++)
        {
            msg = msg + cmItem[i] + "\n";
        }
        MessageBox.Show(msg);

What's the reason of it not working?

Thanks

Answer 1

The solution is to put a

sourceWorkSheet.Sort.SortFields.Clear(); 

before

sourceWorkSheet.Sort.SortFields.Add(sourceWorkSheet.Range["J:J"], XlSortOn.xlSortOnValues, XlSortOrder.xlAscending, XlSortDataOption.xlSortNormal);

Answer 2

In your code you open excel then read from it so sheets are read in original order (not sorted alphabetical). You can use next code to get sorted sheets.

        OleDbConnection connection = new OleDbConnection(string.Format("Provider=Microsoft.ACE.OLEDB.12.0;Data Source={0}; Extended Properties=\"Excel 8.0;HDR=No;\"", filePath));
        OleDbCommand command = new OleDbCommand();
        DataTable tableOfData = null;
        command.Connection = connection;
        try
        {
            connection.Open();
            tableOfData = connection.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
            string tablename = tableOfData.Rows[0]["TABLE_NAME"].ToString();
            tableOfData = new DataTable();
            command.CommandText = "Select * FROM [" + tablename + "]";
            tableOfData.Load(command.ExecuteReader());
        }
        catch (Exception ex)
        {
        }