验证acess中某项内的数据是否存在的有关问题，请高指教一下，多谢

验证acess中某项内的数据是否存在的问题，请高指教一下，谢谢！
我原来的代码为：

<!--#include file="conn2.asp"-->

<%

	dim name,cards,phone,time,network,level,rs

	Name=htmlencode(request.form("Name"))

    cards=htmlencode(request.form("cards"))

    phone=htmlencode(request.form("phone"))

	time=htmlencode(request.form("time"))

	network=htmlencode(request.form("network"))

	level=htmlencode(request.form("level"))

	If name="" or cards="" or phone="" then

		Response.Write "<script>alert('持卡人、卡号，电话不能为空！');this.location.href='vbscript:history.back()';;</SCRIPT>"

	ElseIf len(Name)>5 or len(cards)<21 then

		Response.Write "<script>alert('持卡人、卡号输入错误！');this.location.href='vbscript:history.back()';</SCRIPT>"

	ElseIf len(cards)<21 or len(phone)>13 or len(time)>40 or len(network)>40 then

		Response.Write "<script>alert('卡号必须是19位！、联系电话、必须填写！');this.location.href='vbscript:history.back()';</SCRIPT>"

	ElseIf len(time)>100 then

		Response.Write "<script>alert('申请日期不要大于100个字符！');this.location.href='vbscript:history.back()';</SCRIPT>"

	ElseIf len(level)>400 then

		Response.Write "<script>alert('其它资料不要大于400个字符！');this.location.href='vbscript:history.back()';</SCRIPT>"

	Else

	Set Rs= Server.CreateObject("adodb.recordSet")

	Rs.open "Select * from data", conn, 1, 3

	Rs.addnew

		Rs("Name") = Name

		Rs("cards") = cards

		Rs("phone") = phone

		Rs("network") = network

        Rs("time") = time

		Rs("level") = level

		Rs("ip") = request.serverVariables("remote_host")

	Rs.update

	Rs.close

	Set Rs = nothing

		Response.Write "<script>alert('VIP卡申请成功');this.location.href='add.asp';</SCRIPT>"

		Response.End

	End If

	closedb

%>

现在我想要验证“cards”项内的卡号是否有录入重复，如何重复，则提示并跳转到指定的页面。请高手们帮忙修改一下送分为谢！
------解决方案--------------------
Rs.open "Select * from data WHERE cards='" & cards & "'", conn, 1, 3
IF Not rs.EOF Then
Response.Write "重复cards"
Else
Rs.addnew
        Rs("Name") = Name
        Rs("cards") = cards
        Rs("phone") = phone
        Rs("network") = network
        Rs("time") = time
        Rs("level") = level
        Rs("ip") = request.serverVariables("remote_host")
    Rs.update
    Rs.close
    Set Rs = nothing
        Response.Write "<script>alert('VIP卡申请成功');this.location.href='add.asp';</SCRIPT>"
        Response.End
    End If

End If