用户名注册重复的问题

[huhacoca]

if rs.eof and not rs.bof then
Rs.addnew
Rs("username")=request.Form("username")
Rs("password")=request.Form("psd1")
Rs("address")=request.Form("address")
Rs("tel")=request.Form("tel")
Rs("contact")=request.Form("contact")
Rs("content")=request.Form("content")
Rs("companyname")=request.Form("select")
Rs("time")=now()
Rs.update
Rs.Close
conn.close
Set Rs=nothing
set conn=nothing
response.write("<script language=javascript> alert('注册成功!');window.location.href='login.asp';</script>")
else
response.write("<script language=javascript> alert('用户名重复!');window.location.href='reg.asp';</script>")
end if


改过很多次了，不是可以一直重复添加，就是一直提示用户名重复。。。
求正确的写法

[hookee]

判断没记录的话用 rs.eof and rs.bof

if rs.eof and rs.bof then
   ....
   Rs.update
end if

[不耐烦]

if rs.eof and not rs.bof then

改成

if rs.eof and rs.bof then

[qqm05]

if rs.eof and rs.bof then