Average age of WP Croatia articles

SQL

use enwiki_p;

select count(*), avg(age)
from (
select pa.page_id, 
str_to_date(max(r.rev_timestamp), '%Y%m%d') as ts, 
datediff(date '20210101', str_to_date(max(r.rev_timestamp), '%Y%m%d')) - 1 as age
from page pa 
inner join revision r on r.rev_page = pa.page_id
where pa.page_namespace = 0 and pa.page_is_redirect = 0 and
pa.page_title in 
(
select pt.page_title
from page pt
inner join categorylinks cl on cl.cl_from = pt.page_id
where pt.page_namespace = 1 and cl.cl_to = "WikiProject_Croatia_articles"
) and
r.rev_timestamp < '20210101'
group by pa.page_id
) t

SQL

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