MySQL events were added in MySQL 5.1.6 and offer an alternative to scheduled tasks and cron jobs. Events can be used to create backups, delete stale records, aggregate data for reports, and so on. Unlike standard triggers which execute given a certain condition, an event is an object that is triggered by the passage of time and is sometimes referred to as a temporal trigger . You can schedule events to run either once or at a recurring interval when you know your server traffic will be low.
PHPMaster: Working with MySQL Events