php cron job, or is there an effecient method?

so i want to create a tool on my site that allows users, if 5 users are logged on with unique IPs, to post up a request to play 5 other people ~

so for the verification, i would just store the IP in the database as they login and when they logout, delete it from the database ~

anyways, so the tool that allows people to look for people to play against would check if the team id tied to the user, and see if there are 5 unique ip address. then i would allow them to do the posting

so the problem is how do i do the “update” of the page, meaning people are going to be posting and deleting their requests for players, and maybe someone logs out and so only 4 people are logged in from that team with the same ip, i would want them to be “booted” out of the service with some warning saying 5 people are necessary.

would i do a cron job that updates every minute checking if the people using the tool have 5 logged on? wouldn’t kill my database? is there any more effecient way to do so?

Also in #PHP _↴