由普通用户解决的议题
（可能有一种方法可以将此查询与工作人员查询结合起来。）
在给定时间段内，按类别细分的工作人员解决的议题数量。可以通过编辑此行来更改类别数组：WHERE t.category_id = ANY ('{46,25,43,40,44,35,22,7,20,17,6,12}'::int[])。可以修改查询，使其返回所有类别的结果，或者使类别数组以字符串参数的形式提供，格式为 {1, 2, 3}。
-- [params]
-- int :months_ago = 1
WITH query_period AS (
SELECT
date_trunc('month', CURRENT_DATE) - INTERVAL ':months_ago months' as period_start,
date_trunc('month', CURRENT_DATE) - INTERVAL ':months_ago months' + INTERVAL '1 month' - INTERVAL '1 second' as period_end
)
SELECT
t.category_id,
COUNT(1) AS solved_count
FROM user_actions ua
JOIN topics t
ON t.id = ua.target_topic_id
JOIN query_period qp
ON ua.created_at >= qp.period_start
AND ua.created_at <= qp.period_end
JOIN users u
ON u.id = ua.user_id
WHERE t.category_id = ANY ('{46,25,43,40,44,35,22,7,20,17,6,12}'::int[])
AND ua.action_type = 15
AND (u.admin = 'f' AND u.moderator = 'f')
GROUP BY t.category_id
ORDER BY solved_count DESC