<%
    set rs=server.createobject("adodb.recordset")
    rs.open"select * from class_two",conn,1,1
    %>
    ‘---------以上是查询出第一级下拉列表的内容-----
     ’---------以下是用JS来控制程序--------------
    <script language = "javascript">
    var onecount; //定义onecount对像
    onecount=0;//初始值为0
    subcat = new Array(); //SUBCAT对像是一个新的数组
    <%
    count = 0 '定义count对像初始值为0
    do while not rs.eof '循环表头到表尾
    %>
    subcat[<%=count%>] = new Array("<%=rs("class_two_text")%>","<%=trim(rs("class_one"))%>","<%=trim(rs("class_two"))%>");
    //以上为重点内容，对像数组（subcat[count对像值]）= 新数组内容('字段名0','字段名1','字段名2')记住要对应
    <%
    count = count + 1 '循环count一次，COUNT的值加1
    rs.movenext
    loop
    rs.close
    %>
    onecount=<%=count%>;
    function changelocation(locationid)
     {
     document.form.class_two.length = 0;
     var locationid=locationid;
     var i;
     for (i=0;i < onecount; i++)
    {
     if (subcat[1] == locationid)
     {
    document.form.class_two.options[document.form.class_two.length] = new Option(subcat[0], subcat[2]);
     }
    }
     }
    </script>
    <%
    set rs=server.CreateObject("adodb.recordset")
    rs.open "select * from Class_one" ,conn,1,1
    if rs.eof then
    response.Write"暂无产品一类名称"
    else%>
    产品一类
    <select name="class_one" id="class_one"
    onChange="changelocation(document.form.class_one.options[document.form.class_one.selectedIndex].value)">
     <%do while not rs.eof%>
     <option value="<%=rs("class_one")%>"><%=rs("class_one_text")%></option>
     <%rs.movenext
     loop
     end if
     %>
    </select>
    产品二类
    <select name="class_two"
    onChange="three(document.form.class_one.value,document.form.class_two.options[document.form.class_two.selectedIndex].value)">
    <option value="请选择条件" selected>请选择条件</option>
    </select> <%
    set rs=server.createobject("adodb.recordset")
    rs.open"select * from class_three",conn,1,1
    %> <script language = "javascript">
    var twocount;
    twocount=0;
    subthree = new Array();
    <%
    countb = 0
    do while not rs.eof
    %>
    subthree[<%=countb%>] = new
    Array("<%=rs("class_three_text")%>","<%=trim(rs("class_one"))%>","<%=trim(rs("class_two"))%>","<%=trim(rs("class_three"))%>");
    <%
    countb = countb + 1
    rs.movenext
    loop
    rs.close
    %>
    twocount=<%=countb%>;
    function three(threeid,threeid2)
     {
     document.form.class_three.length = 0;
     var threeid=threeid;
     var threeid2=threeid2;
     var i;
     for (i=0;i < twocount; i++)
    {
     if ((subthree[1] == threeid) & (subthree[2] == threeid2))
     {
    document.form.class_three.options[document.form.class_three.length] = new Option(subthree[0],
    subthree[3]);
     }
    }
     }
    </script>
    产品三类
    <select name="class_three" id="class_three">
    <option value="0" selected>请选择条件</option>
    </select>  [转自：711网络工作室 http://www.tc711.com]