dropdownlist分页

<div class="new-paging" id="">

            <div class="new-tbl-type">

                <div class="new-tbl-cell">

                    <a href="<%=prevurl %>" class="new-a-prve"><span>上一页</span></a>

                </div>

                <div class="new-tbl-cell new-p-re" id="pagelist">

                    <div class="new-a-page">

                        <span class="new-open">1/100</span>

                    </div>

                    <asp:DropDownList ID="pageselect" runat="server" class="new-select" onchange="combocg(this);">

                    </asp:DropDownList>

                </div>

                <div class="new-tbl-cell">

                    <a href="<%=nexturl %>" class="new-a-next"><span>下一页</span></a>

                </div>

            </div>

        </div>

 List<student"> list = null;

           	 List<student"> listst = null;

 		 SqlParameter[] parames = new SqlParameter[0];

		string selsql="select * from student";

     		DataSet ds = SqlHelper.ExecuteDataSet(SqlHelper.SqlConncectionString, CommandType.Text, selSql, parames);

		if (ds != null && ds.Tables[0].Rows.Count > 0)

        	{

           		rowsCount = ds.Tables[0].Rows.Count;

       		 }

                if ((nowPage - 1) * pageSize > rowsCount) nowPage = 1;

                int takecount = rowsCount - (nowPage - 1) * pageSize;

                if (takecount > pageSize)

                    listst = list.Skip((nowPage - 1) * pageSize).Take(pageSize).ToList();

                else

                    listst = list.Skip((nowPage - 1) * pageSize).Take(takecount).ToList();

                foreach (var img in listst)

                {

                    img.C_IMGURL = img.C_IMGURL.Replace(".", "_130_140.");

                }

                pageselect.Items.Clear();

                int pagecount = rowsCount % pageSize > 0 ? rowsCount / pageSize + 1 : rowsCount / pageSize;

                for (int i = 0; i < pagecount; i++)

                {

                    pageselect.Items.Add(new ListItem("第" + (i + 1).ToString() + "页", (i + 1).ToString()));

                }

                rplist.DataSource = listst;

                rplist.DataBind();//绑定Repeater

                url = "/Web/Manage/fenye.aspx?";

                url += "&page=";

                prevurl = nowPage > 1 ? url + (nowPage - 1) : url + "1";

                nexturl = nowPage < pagecount ? url + (nowPage + 1) : url + nowPage;

                pageselect.SelectedValue = nowPage.ToString();