IP banning?

I have just made a IP baner for my site, and I was wondering if this was a good methode of doing it...

SQL_config_ipban="SELECT table_config_ipban.* FROM table_config_ipban WHERE db_ipban_number='" & set_user_IP & "';"

site_record.Open SQL_config_ipban, site_data_base
 if not site_record.EOF then
  if site_record("db_ipban_ID") > 0 then
   response.redirect "error.asp"
  end if
 end if 
site_record.close

This works well, but I want to know if this could cause any problems, or if there is a better way of doing it.

Ok, thanks.

I send banned people to an error page.

A general error is always better as you had a reason to ban someone and giving them a general error will make them think there is a problem with the site rather than them. If they believe there is a problem with the site they are less likely to return and/or continue to return. However, even DSL and Cable users occasionally get IP address changes, so you want to keep it general enough so that another visitor will be inclined to email you about not being able to access the site if they happen to have a banned IP.