Recursion on categorylinks

SQL

with recursive subcats (cur_path, cur_dest) as (
  select distinct cl_to, cl_to from categorylinks where cl_to in ("Lists_of_events")
  union all
  select concat(cur_path, ',', page_title), page_title from categorylinks, page
  join subcats on cl_to = cur_dest
  where cl_type = 'subcat' and cl_from = page_id and not find_in_set(page_title, cur_path)
)

select count(distinct cur_dest) from subcats;

/*
select count(distinct page.page_title) from subcats
join categorylinks on cl_to = subcats.page_title and cl_type = 'page'
join page on cl_from = page_id;
*/

/*
select group_concat(page_title separator '", "') from categorylinks, page
where cl_type = 'subcat' and cl_from = page_id and cl_to = 'History-related_lists'

"History-related_lists_by_country", "Lists_of_history_lists", "Prehistory-related_lists", "Ancient_history-related_lists",
"Middle_Ages-related_lists", "Historical_timelines", "Lists_by_time", "Archaeology-related_lists", "Lists_of_archives",
"Cultural_history-related_lists", "Lists_of_disasters", "Lists_of_events", "Lists_of_expeditions",
"Lists_of_historical_films", "Lists_of_former_entities", "Lists_of_historians", "Lists_of_massacres",
"Lists_by_military_conflict", "Lists_of_monuments_and_memorials", "Lists_of_historic_places",
"Social_history-related_lists", "History-related_lists_of_superlatives"
*/
SQL

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