Documentation 
CREATE VIEW current_wiki AS (
  SELECT a.* 
  FROM wiki AS a
  INNER JOIN (
    SELECT wiki_key, MAX( id ) AS max_id
    FROM wiki
    GROUP BY wiki_key
  ) 
  AS b ON a.wiki_key = b.wiki_key
  AND a.id = b.max_id
  WHERE body <> ''
) 

MySQL said: Documentation 
 #1349 - View's SELECT contains a subquery in the FROM clause