The IS EMPTY
clause tests whether a collection-valued expression has no elements. For example, the query
SELECT c FROM Customer c WHERE c.addresses IS EMPTY
returns only those customers with no addresses.
The MEMBER OF
clause tests whether a value of an entity path expression is a member of a collection valued path expression. The query
SELECT DISTINCT c FROM Customer c, Address a WHERE a MEMBER OF c.addresses
returns only those customers who have addresses.