asp一个登陆问题

<!--#include file="../inc/conndb.asp"-->
<!--#include file="../inc/fy.function.asp"-->
<!--#include file="../inc/md5.asp"-->
<%
ip=getip()
users_name=changechr(request.form("uname"))
users_pwd=MD5(trim(request.form("upwd")),32)

'设置正则表达式
Function isletternumber(strng)
isletternumber = false
Dim regEx, Match ' Create variables.
Set regEx = New RegExp
regEx.Pattern = "^[A-Za-z0-9]+$" ' Sets pattern.
regEx.IgnoreCase = True  ' Set case insensitivity.
Set Match = regEx.Execute(strng)
if match.count then isletternumber= true
End Function

if not isletternumber(users_name) then
response.write (" <script language=JavaScript>{alert('用户名：要求为字母或数字！请重新输入。');location.href = 'javascript:history.back()';} </script>")
response.End
end if

set rs=server.createobject("ADODB.Recordset")
sql="select * from fyh_admin where fyh_user='"&users_name&"'"
rs.open sql,conn,1,1

if rs.eof then
rs.close
set rs=nothing
conn.close
set conn=nothing
Response.Write (" <script language=JavaScript>{alert('用户名错误,请重新登录！');location