title: how to make a trigger from a php page
body: <p>suppose i have a databse exam(id,ststus) now, status is not started,but i want to change status to 'started' after a particular time.
  Now i know, i can write a trigger for this,to change it ,depending on sysdate.</p>
  
  <p>but,as i am making a website in php,so i have to write the code in a php page.</p>
  
  <p>my question is, 
  1) will the trigger work automatically,or i need to at least open that particular page,leave it as it is, then at particular time,it will get refreshed and database will change?</p>
  
  <p>2)how exactly does this trigger work?</p>