C#数据导出到Excel，几种方法

using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.OleDb;
using System.IO;
第一步：引入以上头文件

第二步：以下为导出为excel文件的源代码

        string str = "Provider=Microsoft.Jet.OleDB.4.0;Data Source=" + Server.MapPath("Lily.mdb");//数据库连接字符串
        OleDbConnection conn = new OleDbConnection(str);
        conn.Open();
        OleDbDataAdapter da = new OleDbDataAdapter(vv, conn);        
        DataSet ds = new DataSet();
        da.Fill(ds, "table1");
        DataTable dt = ds.Tables["table1"];
        StringWriter sw = new StringWriter();
        sw.WriteLine("SolarID ,BOM分类 ,项次 ,组装图层 ,BYD图纸编号,用量 ,BYD料号(SAP码) ,中文名称 ,供应商料号, 供应商 ,零件描述 ,值, 客户料号 ");
        foreach (DataRow dr in dt.Rows)
        {
            sw.WriteLine( dr["project_table_solarID"] + "," + dr["bomtype"] + "," + dr["bom_item"] + "," + dr["Sequence"] + "," + dr["DWG_NO"]  + "," + dr["Quantitys"] + "," + dr["byd_sap"] + "," + dr["chi_name"]  + "," + dr["supplier_pn"] + "," + dr["suppliers"] + "," + dr["real_descript"] + "," + dr["valuess"] + ","+ dr["customers"]  );
         // dr["project_table_solarID"] 中project_table_solarID是对应的数据库字段
        //上面的sw.WriteLine中的内容和字段是一一对应的
        }
        sw.Close();
         Response.AddHeader("Content-Disposition", "attachment; filename=test.csv");

        Response.ContentType = "application/ms-excel";

     
        Response.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");
        Response.Write(sw);
        Response.End(); 

-----------------------------------------------------------------------------------------------------------------------------
      如果还有疑问 请加我QQ 43914504  E_mail:lishuangzs@sohu.com
法一：导出到csv文件，存放在服务器端任一路径，然后给客户下载 

优点： 
1、可以进行身份认证后给客户下载，如果放到非web目录就没有对应的url，客户无法随时下载。 
2、也是因为生成了文件，所以占用了服务器的空间，但是可以把文件名存放到数据库，再次给客户下载的时候不需要重复生成文件。 
3、csv文件是文本文件，逗号隔开字段，回车隔开行，易于数据导入导出。 

实现方法： 
   SqlConnection conn=new SqlConnection(System.Configuration.ConfigurationSettings.AppSettings["conn"]); 
   SqlDataAdapter da=new SqlDataAdapter("select * from tb1",conn); 
   DataSet ds=new DataSet(); 
   da.Fill(ds,"table1"); 
   DataTable dt=ds.Tables["table1"]; 
   string name=System.Configuration.ConfigurationSettings.AppSettings["downloadurl"].ToString()+DateTime.Today.ToString("yyyyMMdd")+new Random(DateTime.Now.Millisecond).Next(10000).ToString()+".csv";//存放到web.config中downloadurl指定的路径，文件格式为当前日期+4位随机数 
   FileStream fs=new FileStream(name,FileMode.Create,FileAccess.Write); 
   StreamWriter sw=new StreamWriter(fs,System.Text.Encoding.GetEncoding("gb2312")); 
   sw.WriteLine("自动编号,姓名,年龄"); 
   foreach(DataRow dr in dt.Rows) 
   { 
    sw.WriteLine(dr["ID"]+","+dr["vName"]+","+dr["iAge"]); 
   }