title: How to split three single columns into one big column?
body: <p>I've got this type of data in my Datatable. Imagine that ("2019_WK1", "2019_WK2", "2019_WK3") is the three column names and so i need to take split 2019(year) in one big merged cell, (Upper "WK1", "WK2", "WK3") column cells in C#.</p>
  
  <p>using Excel = Microsoft.Office.Interop.Excel;</p>
  
  <p>Below are my datatable code:</p>
  
  <pre><code>Excel.Application xlApp;
              Excel.Workbook xlWorkBook;
              Excel.Worksheet xlWorkSheet;
              object misValue = System.Reflection.Missing.Value;
              Excel.Range chartRange;
  
              xlApp = new Excel.Application();
              xlWorkBook = xlApp.Workbooks.Add(misValue);
              xlWorkSheet = (Excel.Worksheet)xlWorkBook.Worksheets.get_Item(1);
  
              //add data 
              xlWorkSheet.Cells[1, 1] = "Retailer";
              xlWorkSheet.Cells[1, 2] = "Brand";
              xlWorkSheet.Cells[1, 3] = "2019_WK1";
              xlWorkSheet.Cells[1, 4] = "2019_WK2";
              xlWorkSheet.Cells[1, 5] = "2019_WK3";
  
  
              xlWorkSheet.Cells[2, 1] = "Lulu";
              xlWorkSheet.Cells[2, 2] = "Perisil";
              xlWorkSheet.Cells[2, 3] = "25";
              xlWorkSheet.Cells[2, 4] = "26";
              xlWorkSheet.Cells[2, 5] = "23";
  
          xlWorkSheet.Cells[3, 1] = "Lulu";
              xlWorkSheet.Cells[3, 2] = "Ariel";
              xlWorkSheet.Cells[3, 3] = "26";
              xlWorkSheet.Cells[3, 4] = "28";
          xlWorkSheet.Cells[3, 5] = "29";
  
          xlWorkSheet.Cells[4, 1] = "Danube";
              xlWorkSheet.Cells[4, 2] = "Omo";
              xlWorkSheet.Cells[4, 3] = "27";
              xlWorkSheet.Cells[4, 4] = "28";
          xlWorkSheet.Cells[4, 5] = "30";
  
          xlWorkSheet.Cells[5, 1] = "Danube";
              xlWorkSheet.Cells[5, 2] = "Tide";
              xlWorkSheet.Cells[5, 3] = "24";
              xlWorkSheet.Cells[5, 4] = "23";
          xlWorkSheet.Cells[5, 5] = "29";
  
          xlWorkSheet.Cells[6, 1] = "Bin Dawood";
              xlWorkSheet.Cells[6, 2] = "Perisil";
              xlWorkSheet.Cells[6, 3] = "26";
              xlWorkSheet.Cells[6, 4] = "27";
          xlWorkSheet.Cells[6, 5] = "28";
  
  xlWorkBook.SaveAs("d:\\csharp.net-informations.xls", Excel.XlFileFormat.xlWorkbookNormal, misValue, misValue, misValue, misValue, Excel.XlSaveAsAccessMode.xlExclusive, misValue, misValue, misValue, misValue, misValue);
              xlWorkBook.Close(true, misValue, misValue);
              xlApp.Quit();
  
              releaseObject(xlApp);
              releaseObject(xlWorkBook);
              releaseObject(xlWorkSheet);
  
              MessageBox.Show("File created !");
          }
  </code></pre>
  
  <p>I need like this type of columns</p>
  
  <pre><code>  ____________________________
    |            2019           |
    |___________________________|
    |  WK1   l   WK2  l   WK3   |
    |________l________l_________|
    |  25    |   26   |   23    |
    |  27    |   29   |   24    |
    ___24________25_______22_____
  </code></pre>