public static Stream DataSetToExcel(DataSet _SourceDt,string _sheetName)    {      HSSFWorkbook workbook = new HSSFWorkbook();      MemoryStream MS = new MemoryStream();      string [] sheetNames= _sheetName.Split(',');      for(int i = 0; i <sheetNames.Length;i++)      {        HSSFSheet sheet = workbook.Cretesheet(sheetNames[i]);        HSSFRow headRow = sheet.CreateRow(0);        foreach(DataColumn column in _SourceDt.Table[i].cloumns)        headRow.createCell(column.Ordinal).SetCellValue(column.Column.Name);        int rowIndex =1;        foreach(DataRow row in _SourceDt.Tables[i].Rows)        {          HSSFRow dataRow = sheet.CreateRow(rowIndex);          foreach(DataColumn column in _SourceDt.Tables[i].Columns)          {            dataRow.CreateCell(column.Ordinal).SetCellValue(row[column].ToString());          }          rowIndex++;        }      }      workbook.write(MS);      MS.Flush();      MS.Position = 0;      workbook = null;      return MS;    }

   DataTable dt = new DataTable();      DataSet DataTemp = new DataSet();      dt.Columns.Add("列名1",string);      dt.Columns.Add("列名2",string );      for(int i = 0;i<3;i++)      {        DataRow DR = dt.NewRow();        DR["列名1"] = "DATA1";        DR["列名2"] = "DATA1";        dt.Rows.Add(DR);      }      DataTemp.Tables.Add(dt);