Untitled query

SQL

SELECT 
    old_user.user_name AS old_user_name,
    renamed.new_user_name AS new_user_name,
    p.page_title AS subpage_title
FROM 
    user old_user
JOIN 
    page p
ON 
    p.page_title LIKE CONCAT(old_user.user_name, '/%')
JOIN 
    (
        SELECT 
            REPLACE(log_title, '_', ' ') AS old_user_name,
            SUBSTRING_INDEX(SUBSTRING_INDEX(log_params, '\n', -1), '=', -1) AS new_user_name
        FROM 
            logging
        WHERE 
            log_type = 'renameuser'
    ) renamed
ON 
    old_user.user_name = renamed.old_user_name
WHERE 
    p.page_namespace = 2
AND 
    NOT EXISTS (
        SELECT 1
        FROM page p2
        WHERE 
            p2.page_namespace = 2
        AND 
            p2.page_title = p.page_title
        AND 
            p2.page_title LIKE CONCAT(renamed.new_user_name, '/%')
    )
ORDER BY 
    old_user.user_name, p.page_title;
SQL

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