You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near ' c.alias) ELSE  END as slug
FROM #__categories as c
LEFT JOIN  (SELECT cat.id a' at line 4 SQL=SELECT c.id, c.asset_id, c.access, c.alias, c.checked_out, c.checked_out_time,
			c.created_time, c.created_user_id, c.description, c.extension, c.hits, c.language, c.level,
			c.lft, c.metadata, c.metadesc, c.metakey, c.modified_time, c.note, c.params, c.parent_id,
			c.path, c.published, c.rgt, c.title, c.modified_user_id, c.version, CASE WHEN CHAR_LENGTH(c.alias) != 0 THEN CONCAT_WS(':', , c.alias) ELSE  END as slug
FROM #__categories as c
LEFT JOIN  (SELECT cat.id as id FROM #__categories AS cat JOIN #__categories AS parent ON cat.lft BETWEEN parent.lft AND parent.rgt WHERE parent.extension = 'com_content' AND parent.published != 1 GROUP BY cat.id) AS badcats ON badcats.id = c.id
LEFT JOIN #__categories AS s ON (s.lft <= c.lft AND s.rgt >= c.rgt) OR (s.lft > c.lft AND s.rgt < c.rgt)
WHERE (c.extension='com_content' OR c.extension='system') AND c.access IN (1,1,5) AND c.published = 1 AND badcats.id is null AND s.id=22
GROUP BY c.id, c.asset_id, c.access, c.alias, c.checked_out, c.checked_out_time,
			 c.created_time, c.created_user_id, c.description, c.extension, c.hits, c.language, c.level,
			 c.lft, c.metadata, c.metadesc, c.metakey, c.modified_time, c.note, c.params, c.parent_id,
			 c.path, c.published, c.rgt, c.title, c.modified_user_id, c.version
ORDER BY c.lft