Use of non-existing templates in cswiki

SQL

USE cswiki_p;
SELECT * FROM (
  SELECT tl_title, tl_namespace FROM (SELECT DISTINCT tl_title, tl_namespace) AS templates
  WHERE templates.tl_title NOT IN (SELECT page_title FROM page WHERE page_namespace = templates.tl_namespace)
) AS a
JOIN templatelinks AS b ON b.tl_title = a.tl_title AND b.tl_namespace = a.tl_namespace
WHERE b.tl_from_namespace = 0;
/*
SELECT * FROM templatelinks
LEFT JOIN page AS templates ON templates.page_title = tl_title AND templates.page_namespace = tl_namespace
JOIN page AS articles ON articles.page_id = tl_from
WHERE templates.page_id IS NULL
LIMIT 1;*/

SQL

Checking query status...