网络小说教程:asp编程问题

小弟刚学asp编程,要做一个多条件查询的页面.在设置查询数据库(acess)语句的时候弄乱了,高手帮我写完整发到我邮箱weiyoufu@188.com好吗？谢谢啦,发给我正确的我会追加分数的.
<%
ruyimdb="mail.asp"
set conn=server.CreateObject("adodb.connection")
DBPath = Server.MapPath(ruyimdb)
conn.open "provider=microsoft.jet.oledb.4.0; data source="&DBpath
%><title>如意邮箱业务数据查询系统</title>
<form name="haoma" method="post" action="">
<div align="center">
<select size="1" name="dishi" style="font-size: 9pt">
<option value=" ">请选择地市</option>
<option value=" ">所有地市</option>
<%
sql = "select * from lm where lm<>'' order by id asc"
Set rs = Server.CreateObject("ADODB.RecordSet")
rs.Open sql,conn,1,1
while not rs.eof
%>
<option value='<%=rs("so")%>'><%=rs("lm")%></option>
<%
sql2 = "select * from lm where lmid=1 order by id asc"
Set rs2 = Server.CreateObject("ADODB.RecordSet")
rs2.Open sql2,conn,1,1
while not rs2.eof
%>

<%
rs2.movenext
wend
rs.movenext
wend
rs.close
set rs=nothing
%>

</select>
<input type="submit" name="Submit" value="开始查询" />
</div>
</form>
<%
dishi=trim(request("dishi"))
sql = "select * from mail"
if dishi="" then
sql=sql
else
sql=sql&" where quhao='"&dishi&"'"
end if
Set rs = Server.CreateObject("ADODB.RecordSet")
rs.Open sql,conn,1,1
do while not rs.eof
%>
<%=rs("quhao")%><BR>
<%
rs.movenext
loop
rs.Close
%>
数据库名是mail.asp
有这么几个字段:id(自动编号)ronglian(容量-数字)tel(手机号-数字)time(注册时间-时间/日期)fangshi(注册方式-文本)quhao(地市区号-数字)