怎么将数据库数据导入excel出错 求教高手
public void CreateExcel(DataSet ds)
  {
  HttpResponse resp;
  resp = Page.Response;
  resp.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");
  resp.AppendHeader("Content-Disposition", "attachment;filename=filename.xls");
   
  Response.ContentType = "application/ms-excel";

  string colHeaders = "", ls_item = "";
  DataTable dt = ds.Tables["0"];
  DataRow[] myRow = dt.Select();
  int i;
  int cl = dt.Columns.Count;
  for (i = 0; i < cl; i++)
  {
  if (i == cl - 1)
  {
  colHeaders += dt.Columns[i].Caption.ToString() + "\n";
  }
  else
  {
  colHeaders += dt.Columns[i].Caption.ToString() + "\t";
  }
  }
  resp.Write(colHeaders);

  foreach (DataRow row in myRow)
  {
  for (i = 0; i < cl; i++)
  {
  if (i == (cl - 1))
  {
  ls_item += row[i].ToString() + "\t";
  }
  else
  {
  ls_item += row[i].ToString() + "\n";
  }
  }
  resp.Write(ls_item);
  ls_item = "";
  }
  resp.End();
   
  }

按钮事件--------------------------------

 protected void id1_Click(object sender, EventArgs e)
  {
  SqlConnection con = new SqlConnection("server=WWW-37894A7821D;uid=sa;pwd=123;database=COLWAP");
  con.Open();
   
  SqlDataAdapter da = new SqlDataAdapter("select * from service_base_question_key",con);
  DataSet ds = new DataSet();
  da.Fill(ds, "service_base_question_key");
   
  CreateExcel(ds);
  }

为什么我点击按钮的时候会提示我“未将对象引用设置到对象的实例” 就是在 DataRow[] myRow = dt.Select();这段代码

求教高手  


------解决方案--------------------

C# code

//导出excel的公共方法
    public void ExportData(DataSet ds, string xlsName)
    {
        try
        {
            XlsDocument xls = new XlsDocument();
            xls.FileName = xlsName;

            int rowIndex = 1;
            int colIndex = 0;

            DataTable table = ds.Tables[0];


            Worksheet sheet = xls.Workbook.Worksheets.Add("导出资源");//状态栏标题名称
            Cells cells = sheet.Cells;
            foreach (DataColumn col in table.Columns)
            {
                colIndex++;
                //sheet.Cells.AddValueCell(1,colIndex,col.ColumnName);//添加XLS标题行
                cells.Add(1, colIndex, col.ColumnName.ToString());

            }

            foreach (DataRow row in table.Rows)
            {
                rowIndex++;
                colIndex = 0;
                foreach (DataColumn col in table.Columns)
                {
                    colIndex++;
                    //sh