I want my registration form to make sure that if the username already exists in my local storage, the user will not be able to register unless they change their username to something that hasn't been taken. Any ideas? I have already done nearly everything but just that part im stuck on.
Before storing the details to your database, run a query to check if username exists in the database. First, the query should be directed only to the username row, then use a loop to check if the newly inputed username is in the database. If it is, just tell the user to change username.