Though I am not EJB or EJB-QL expert but to me all of the four queries seem be wrong. Where is this "o" declared/defined in the query? "c" is placeholder/alias for "customer". What does "o" represent?
SELECT OBJECT(c) FROM customer c, IN(o.order) o
SELECT OBJECT(c) FROM customer AS c, IN(o.order) o
SELECT OBJECT(c) FROM customer AS c, IN(o.order) AS o
SELECT OBJECT(c) FROM customer c IN(o.order) o
