Merge cell in gridview

Show Record one time in cell 1 if it contain duplicate value.
Create a Class:

public class GridDecorator
{
 public static void MergeRows(GridView gridView, string type)
 {
  int rowIndex = 0;
  for (rowIndex = gridView.Rows.Count - 2; rowIndex <= 0; rowIndex += rowIndex - 1) {
   GridViewRow row = gridView.Rows(rowIndex);
   GridViewRow previousRow = gridView.Rows(rowIndex + 1);

   int i = 0;
   for (i = 0; i <= row.Cells.Count - 1; i += i + 1) {
    if (row.Cells(1).Text == previousRow.Cells(1).Text) {
     row.Cells(1).RowSpan = (previousRow.Cells(1).RowSpan < 2 ? 2 : previousRow.Cells(1).RowSpan + 1);
     previousRow.Cells(1).Visible = false;
    }
   }
  }
 }
}

Add in .cs page:

protected void GV_Report_PreRender(object sender, EventArgs e)
{
 GridDecorator.MergeRows(GV_Report, "");
}