add Hibernate object states: Transient/Persistent/Detached
add CascadeType/FetchType for many to one bidirectional associations
add set/list/map for Collection mapping
add Inheritance mapping
add tree model for one to many bidirectional associations
add HQL/EJBQL/QBC/QBE sample1 test
add 1+N question for hibernate
add pessimistic/optimistic lock for hibernate