title: MySQL update if record does not exists in other table
body: <p>I am trying to figure out if it is possible to check if a specific record exists in table B. if so, don't update table A.</p>
  
  <p>I have tried googling, but I only find the insert version and I'm not sure if it's even possible with an update query.</p>
  
  <p>Thanks in advance</p>