Sql数据保存到Excel文件中

        /// <summary>
        /// 把数据库中的数据保存到Excel文件中，需要先安装excel
        /// </summary>
        /// <param name="ds"></param>
        /// <param name="saveFileName"></param>
        /// <returns></returns>
        public string ExportExcel(DataSet ds, string saveFileName)
        {
            try
            {
                if (ds == null)
                    return "数据库为空";

                bool fileSaved = false;
                Microsoft.Office.Interop.Excel.Application xlApp = new Microsoft.Office.Interop.Excel.Application();

                if (xlApp == null)
                {
                    return "无法创建Excel对象，可能您的机子未安装Excel";
                }

                Microsoft.Office.Interop.Excel.Workbooks workbooks = xlApp.Workbooks;
                Microsoft.Office.Interop.Excel.Workbook workbook = workbooks.Add(Microsoft.Office.Interop.Excel.XlWBATemplate.xlWBATWorksheet);
                Microsoft.Office.Interop.Excel.Worksheet worksheet = (Microsoft.Office.Interop.Excel.Worksheet)workbook.Worksheets[1];//取得sheet1
                //写入字段
                for (int i = 0; i < ds.Tables[0].Columns.Count; i++)
                {
                    worksheet.Cells[1, i + 1] = ds.Tables[0].Columns[i].ColumnName;
                }
                //写入数值

                for (int r = 0; r < ds.Tables[0].Rows.Count; r++)
                {
                    for (int i = 0; i < ds.Tables[0].Columns.Count; i++)
                    {
                        worksheet.Cells[r + 2, i + 1] = ds.Tables[0].Rows[r][i];
                    }
                    System.Windows.Forms.Application.DoEvents();
                }  
                worksheet.Columns.EntireColumn.AutoFit();//列宽自适应。
                if (saveFileName != "")
                {
                    try
                    {
                        workbook.Saved = true;
                        workbook.SaveCopyAs(saveFileName);
                        fileSaved = true;
                    }
                    catch (Exception ex)
                    {
                        fileSaved = false;
                        MessageBox.Show("导出文件时出错,文件可能正被打开！\n" + ex.Message);
                    }
                }
                else
                {
                    fileSaved = false;
                } 
                //把文件先变成二进制流，删除文件，然后把此excel推向客户端下载
                string fileAllPath = saveFileName;
                FileStream fsManuscript = new FileStream(fileAllPath, FileMode.Open, FileAccess.Read, FileShare.Read);//打开文件
                int rgfilesize = Convert.ToInt32(fsManuscript.Length);
                byte[] byteArrManuscriptContent = new byte[rgfilesize];
                fsManuscript.Read(byteArrManuscriptContent, 0, rgfilesize);//读取文件
                fsManuscript.Close();
                fsManuscript.Dispose();

                //删除文件
                if (File.Exists(fileAllPath))
                {
                    File.Delete(fileAllPath);
                }
                //下载文件
                string downloadFileName = saveFileName;
                System.Web.HttpContext.Current.Response.ContentType = "application/vnd.ms-excel";//设置输出为Excel文件
                System.Web.HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.UTF8;//输出流设置为简体中文
                System.Web.HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(downloadFileName, System.Text.Encoding.UTF8) + ";");
                System.Web.HttpContext.Current.Response.BinaryWrite(byteArrManuscriptContent);//将2进制字符串写入HTTP输出流
                System.Web.HttpContext.Current.Response.End();//将缓冲的输出流发送到客户端
                //xlApp.DisplayAlerts = false;//防止弹出提示框
                //xlApp.AlertBeforeOverwriting = false;//保存工作簿
                xlApp.Quit();
                return "成功保存到Excel";
            }
            catch (Exception ex)
            {
                return ex.ToString();
            }
        }