if
 isnull((select lastClick
  from clicks
  where adoptableID=new.adoptableID
  and userID=new.userID)) then
  insert into clicks(userID,adoptableID,lastClick)
  values(new.userID,new.adoptableID,new.lastClick)
elseif addtime(
  (select lastClick from clicks
   where adoptable.ID=new.adoptableID
   and userID=new.userID), '24:00') <= CURRENT_TIMESTAMP
  then
  update clicks
   set lastClick=CURRENT_TIMESTAMP
  where userID=new.userID
  and adoptableID=new.adoptableID;
else
   signal sqlstate '45000' set message_text='You must wait one day between clicks.';
END IF