title: MySQL - Update with CASE and ELSE
body: <p>I'm developing a small MySQL database about driving licenses. I made a random list with 500 registers where I have a type of license (Moto[A],Car[B],Bus[C],Truck[D],Special[E]) and a random expedition date.</p>
  
  <p>Well now I want to poblate a new column with "expiration_date", with a conditional that if the driving type is D or E the expiration date should be 5 years, and 10 the rest.</p>
  
  <p>The syntax I made is</p>
  
  <pre><code>UPDATE db.carnets 
  SET date_expiration =
  CASE WHEN carnet_type = "D" OR carnet_type = "E" THEN DATE_ADD(date_expiration, INTERVAL 5 YEAR)
  ELSE DATE_ADD(date_expiration, INTERVAL 10 YEAR)
  </code></pre>
  
  <p>It shows the generic MySQL error on line 4 [Else date_add....]. 
  Where is the error?</p>
  
  <p>Thank you.</p>