Average age of WP Croatia articles

SQL

use enwiki_p;

# 20200101: 15245/325.0
# 20210101: 15736/291.0
# 20210110: 15745/285.3
# 20210120: 15756/277.8
# 20210201: 15769/272.7
# 20210210: 15816/274.1
# 20210220: 15872/273.5
# 20210301: 15882/276.1
# 20210310: 15891/278.7
# 20210320:
select count(*), round(avg(age), 1) as avg_age
from (
  select pa.page_id, 
  str_to_date(max(r.rev_timestamp), '%Y%m%d') as ts, 
  datediff(date '20210320', 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 < '20210320'
  group by pa.page_id
) t
SQL

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