-- [params]
-- int :months_since_used = 24
-- int :max_topic_count = 50
with
t as (
select
current_date::timestamp - (:months_since_used * (INTERVAL '1 months')) as cutoff_date
),
topic_tag_dates as (
select tags.id, tags.name, tags.topic_count, topics.last_posted_at as last_used
from topic_tags
left join tags
on topic_tags.tag_id = tags.id
left join topics
on topic_tags.topic_id = topics.id
),
max_last_used as(
select id, max(last_used) mx from topic_tag_dates
group by id
),
tag_last_used as (
select topic_tag_dates.id, name, topic_count, last_used from topic_tag_dates
left join max_last_used
on topic_tag_dates.id = max_last_used.id
where max_last_used.mx = topic_tag_dates.last_used
)
select id,name,topic_count,last_used from tag_last_used, t
where tag_last_used.last_used < t.cutoff_date
and topic_count < :max_topic_count
order by topic_count desc