导出Excel多个表多个sheet

protected void Page_Load(object sender, EventArgs e)    {
       DataTable dt = new DataTable();    
   DataColumn dc = new DataColumn("id");     
  dt.Columns.Add(dc);      
 dc = new DataColumn("name");  
     dt.Columns.Add(dc);    
   dt.Rows.Add("1", "a");    
   dt.Rows.Add("2", "b");    
   dt.Rows.Add("3", "c");     
  DataTable dt1 = new DataTable();   
    DataColumn dc1 = new DataColumn("id");    
   dt1.Columns.Add(dc1);   
    dc1 = new DataColumn("name");   
    dt1.Columns.Add(dc1);  
     dt1.Rows.Add("4", "j");   
    dt1.Rows.Add("5", "k");    
   dt1.Rows.Add("6", "l");      
 DataSet ds = new DataSet();   
    ds.Tables.Add(dt);   
    ds.Tables.Add(dt1);    
   ConvertToExcel(ds); 
  }

public string ConvertToExcel(DataSet ds)    {     
  string FilePath;   
    Microsoft.Office.Interop.Excel.ApplicationClass ExcelApp = new Microsoft.Office.Interop.Excel.ApplicationClass();        ExcelApp.Application.Workbooks.Add(Type.Missing);   
    DataTable dt = ds.Tables[0];     
  DataTable dt1 = ds.Tables[1];     
  Microsoft.Office.Interop.Excel.Worksheet Sheet1 = (Microsoft.Office.Interop.Excel.Worksheet)ExcelApp.Sheets[1];   
    for (int i = 0; i < dt.Columns.Count; i++)     
  {          
 Sheet1.Cells[1, i + 1] = dt.Columns[i].ColumnName;   
    }      
 for (int i = 0; i < dt.Rows.Count; i++)  
     {         
  for (int j = 0; j < dt.Columns.Count; j++)     
      {             
  Sheet1.Cells[i + 2, j + 1] = dt.Rows[i][j].ToString();   
        }   
    }      
 Microsoft.Office.Interop.Excel.Worksheet Sheet2 = (Microsoft.Office.Interop.Excel.Worksheet)ExcelApp.Sheets[2];    
   for (int i = 0; i < dt1.Columns.Count; i++)    
   {            Sheet2.Cells[1, i + 1] = dt1.Columns[i].ColumnName;        }     
  for (int i = 0; i < dt1.Rows.Count; i++)     
  {            for (int j = 0; j < dt1.Columns.Count; j++)  
         {                Sheet2.Cells[i + 2, j + 1] = dt1.Rows[i][j].ToString();    
       }    
   }      
 FilePath = "d:\\" + Guid.NewGuid() + ".xls";      
 if (FilePath != string.Empty)      
 {            ExcelApp.ActiveWorkbook.SaveAs(FilePath, Microsoft.Office.Interop.Excel.XlFileFormat.xlExcel5, null, null, false, false, Microsoft.Office.Interop.Excel.XlSaveAsAccessMode.xlNoChange, null, null, null, null, null);    
       ExcelApp.ActiveWorkbook.Saved = true;      
     ExcelApp.Quit();    
   }   
    return FilePath;  
 }