Checking and saving IP in database

I want to make an "if-else statement"

if (check if the users ip is in db)

else (some action, save the users ip and it should be thrown out after an hour)

I could someone explain this to me? How I should do this.

Update:

I know I've to use $_SERVER['REMOTE_ADDR'], but when I echo this, I get ::1. I guess from 127.0.0.1. But would this work when I save the ip of my visitors that way?

Update:

I know I've to use $_SERVER['REMOTE_ADDR'], but when I echo this, I get ::1. I guess from 127.0.0.1. But would this work when I save the ip of my visitors that way?

If you managed to get ::1 in the database whilst using localhost, then yes, it will work.