UPDATE fsb2_users u SET u.u_total_post = (
     SELECT COUNT(p.*)
     FROM fsb2_posts p
     WHERE p.u_id = u.u_id
), u.u_total_topic = (
     SELECT COUNT(t.*)
     FROM fsb2_topics t
     WHERE t.u_id = u.u_id
);

requête SQL: Documentation

UPDATE fsb2_users u SET u.u_total_post = ( SELECT COUNT( p . * )
FROM fsb2_posts p
WHERE p.u_id = u.u_id ) , u.u_total_topic = (
SELECT COUNT( t . * )
FROM fsb2_topics t
WHERE t.u_id = u.u_id )

MySQL a répondu:Documentation
#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '*)
     FROM fsb2_posts p
     WHERE p.u_id = u.u_id
), u.u_t 

UPDATE fsb2_users u SET u.u_total_post = (
     SELECT COUNT(p.u_id)
     FROM fsb2_posts p
     WHERE p.u_id = u.u_id
), u.u_total_topic = (
     SELECT COUNT(t.u_id)
     FROM fsb2_topics t
     WHERE t.u_id = u.u_id
);