-- Find categories not directly or indirectly linked to Category:Category

SELECT 

  p.page_title AS "Orphaned Category"

FROM page p

-- Check for direct linkage to Category:Category

LEFT JOIN categorylinks cl_root 

  ON p.page_id = cl_root.cl_from 

  AND cl_root.cl_to = 'Category' 

  AND cl_root.cl_type = 'subcat'

-- Check for indirect linkage via 1 intermediate category

LEFT JOIN categorylinks cl_indirect 

  ON p.page_id = cl_indirect.cl_from 

  AND cl_indirect.cl_type = 'subcat'

LEFT JOIN page p_indirect 

  ON cl_indirect.cl_to = p_indirect.page_title 

  AND p_indirect.page_namespace = 14

LEFT JOIN categorylinks cl_indirect_root 

  ON p_indirect.page_id = cl_indirect_root.cl_from 

  AND cl_indirect_root.cl_to = 'Category' 

WHERE 

  p.page_namespace = 14              -- Category namespace

  AND p.page_title != 'Category'     -- Exclude root

  AND cl_root.cl_from IS NULL        -- No direct link to root

  AND cl_indirect_root.cl_from IS NULL -- No indirect link via 1 intermediate

LIMIT 5000;