三级联动下拉列表[数据库版] 带注释

<%
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]
        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> </td>