我用这段代码写入数据库为什么出错???
<%set rs=server.createobject("adodb.recordset"

        sql="select * from loginfo where (id is null)"
        rs.open sql,conn,1,3    
               if rs.eof then
    rs.addnew
    rs("username"

=username
    rs("password"

=password
    rs("email"

=email
    rs("sex"

=sex
    rs.update
    end if
%>