How to implement date-based events on the site?

Question

PHP

I am currently studying web development and I have a question.
Let's say I have records on my site that I store in the MySQL database. Each record has an expiration date. When it expires, the entry must be deleted.
Or another example - I have a database with the date of birth of users, and I want to congratulate them on their birthday in a timely manner by sending them an email, for example. How is it implemented? Where to read on this subject?

Answer 1

For example, through cron.