//从DataSet到出到Excel
    protected void Button1_Click(object sender, EventArgs e)
    {
        string sqlStr = "select * from IoApply ";
     //string sqlStr = "select id as 序号,(case Gender when 0 then '女' when 1 then '男' end) as 性别  from OpenDay order by RegisterTime desc";
            DataTable DtOut = DataAccess.ExecuteSql("OpenDay.ConnectionString", sqlStr).Tables[0];
            Response.Clear();
            Response.ContentEncoding = Encoding.Default;
            Response.AppendHeader("content-disposition", "attachment; filename=" + HttpUtility.UrlEncode("OpenDay"+System.DateTime.Now.ToString("MM.dd")+".xls"));
            Response.ContentType = "application/octet-stream";

for (int i = 0; i < DtOut.Columns.Count; i++)
            {
                Response.Write(DtOut.Columns[i].ColumnName.ToString() + "\t");
            }

Response.Write(Environment.NewLine);
            for (int i = 0; i < DtOut.Rows.Count; i++)
            {
               
                StringBuilder sb = new StringBuilder();
                for (int j = 0; j < DtOut.Columns.Count; j++)
                {
                    sb.Append(DtOut.Rows[i][j].ToString());
                    sb.Append("\t");
                }
                Response.Write(sb.ToString());
                Response.Write(Environment.NewLine);
            }

Response.End();
        }     
       
    }