title: How to create update trigger?
body: <p>I have a very simple question, so I hope someone will help.</p>
  
  <p>I have a MySQL table with ID and CREDIT. I want to do an update trigger, which would change the update value if credit is 0. So something like "if old.CREDIT = 0 then new.CREDIT = 0.001". So what will be the syntax of the trigger? Thanks.</p>