How to check the number of user reputation before storing his vote via trigger

问题

I have two tables. Posts, Votes. I have a column in the Posts table named total_votes. Also I have a trigger for updating it when user gives a vote to the post.

Here is my trigger:

delimiter //
CREATE TRIGGER total_votes AFTER INSERT ON Votes
 FOR EACH ROW begin 
   update posts set total_votes = total_votes+new.value
   where  post.id = new.post_id; 
end //

So I need to check the number of user reputation, that If they are more than 50, then the vote stores, else, the vote not store. how can I do that ?

Actually I can write this: BEFORE INSERT

If ((select reputation from users where id = new.user_id) < 50) then
  SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'your rep are low';
end if;

Now I have two problem, One: how can I use of that error (your rep are low) in my website ? (via php), and two: How can I deactivate total_votes trigger (AFTER INSERT) if the above condition was true ?

来源：https://stackoverflow.com/questions/32157945/how-to-check-the-number-of-user-reputation-before-storing-his-vote-via-trigger