聚合相当复杂的联接

Question

I have the following query: That I've just noticed isn't aggregating user's counts for when they have 0 item_count . I have tried to adjust this query as i've made this mistake before, but not with this more complex kind of query, how would i need to adjust this in order for it to show a user's item_count even if 0??

SELECT u.ID AS user_id,
                u.date_expired AS user_date_expired,
                u.first_name AS first_name,
                u.last_name AS last_name,
                COUNT(i.id)    AS item_count
FROM `user` `u`
LEFT JOIN `item` `i` ON i.recruiter_id = u.id
WHERE ((`u`.`id` IN ('15', '2', 13)) AND (i.date_added >
DATE_SUB(u.date_expired, INTERVAL  30 DAY)))
GROUP BY `u`.`id`

Thanks

Jonny

Answer 1

Try it this way

SELECT u.id           AS user_id,
       u.date_expired AS user_date_expired,
       u.first_name   AS first_name,
       u.last_name    AS last_name,
       COUNT(*)       AS item_count
  FROM user u LEFT JOIN item i 
    ON i.recruiter_id = u.id
   AND i.date_added > u.date_expired - INTERVAL  30 DAY
 WHERE u.id IN (15, 2, 13) 
 GROUP BY u.id, u.date_expired, u.first_name, u.last_name