Oracle Java EE 6 Java Persistence API Developer Certified Expert

문제1
A developer has created a deep entity class hierarchy with many polymorphic relationships between entitles. Which inheritance strategy, as defined by the inheritanceType enumerated type, will be most performed in this scenario?

A. Table-per-concrete-class (inheritanceType.TABLE_PER_CLASS)

B. Polymorphic join table (inheritanceType. POLYMORPHIC_JOIN_TABLE)

C. Single table-per-class-hierarchy (InheritanceType.SINGLE_TABLE)

D. Joined-subclass (inheritanceType. JOINED)

정답: A

문제2
An application has two entities, Department and Employee, and there is a one-to-many relationship between them. The application has the following query:
SELECT d
FROM Department d LEFT JOIN FETCH d. employees
WHERE d.name = : name
After receiving the results of the query, the application accesses the returned department's Employee entities stored in the Department.employees collection-valued attribute.
All caching has been turned off in the application.
Which statement is true?

A. The database will be accessed once during the query execution phase ONLY.

B. The database will be accessed once during the query execution phase, and once when the department.employees collection-valued attribute is used.

C. The database will be accessed once during the query execution phase, once when the Department. Employees collection-valued attribute is used, and once for each employee entity in the Department.employees.

D. The database will be accessed once during the query execution phase, and once for each Employee entity in Department - employees.

정답: B

문제3
An entity person is mapped to a table PERSON and has a collection-valued persistence field otherUsedNames that stores names used by a person. The other used Names field is mapped to a separate table called NAMES. Which code fragment correctly defines such field?

A. @ElementCollection
@SecondaryTable (names = "NAMES")
Protected set<String> otherUsedNames = new HashSet () ;

B. @ElementCollection (name = "NAMES")
Protected set<String> otherUsedNames = new HashSet () ;

C. @Element collection
@ElementTable (name = "NAMES")
Protected set<String> otherUsedNames = new HashSet () ;

D. @ElementCollection
@CollectionTable(names = "Names")
Protected set<String> otherUsedNames = new HashSet () ;

정답: D

설명: (KoreaDumps 회원만 볼 수 있음)

문제4
Which one of the following queries selects the customer whose order has the highest total price?

A. CriteriaBuilder cb = ...
CriteriaQuery<Customer> cq = cb.createQuery(Customer.class);
Root<Customer> c = cq.from(Customer.class);
Join<Customer, Order> o = c.join(Customer_.orders);
cq.select(c).distinct(true);
Subquery<Double> sq = cq.subquery(Double.class);
Root<Order> subo = sq.from(Order.class);
sq. select (ci: . max ( subo . get (Order_ . Total Price) ) ) ;
cq.where(sq.all(o.gei(Order_.totalPrice)));

B. CriteriaBuilder cb = ...
CriteriaQuery<Customer> cq = cb.cteateQuery(Customer.class);
Root<Customer> c = cq.from(Customer.class);
Join<Customer, Order> o = c.join(Customer__.orders);
cq.select(c).distinct(true);
Subquery<Double> sq = cq.subquery(Double.class);
Root<Order> subo = cq.correlate(o);
sq.select(cb.max(subo.get(Order_.totalPrice)));
cq.where(cb.equal(o.get(Order_.totalPrice), cb.all(sq)));

C. CriteriaBuilder cb = ...
CriteriaQuery<Customer> cq = cb.createquery(customer.class)
Root<Customer> c = cq.from(Customer.class);
Join<Customer, Order> o = c.join(Customer__.orders);
cq.select(c).distinct(true);
Subquery<Double> sq = cq.subquery(Double.class);
Root<Order> subo = cq.correlate(o);
sq.select(cb.max(subo.get(Order_.totalPrice)));
cq.where(cb.equal(o.get(Order_.totalPrice), cb.all(sq)));

D. CriteriaBuilder cb = ...
Criteria Query <Customer> cq = cb.create Query (Customer.class);
Root<Customer> c = cq.from(Customer.class);
Join<Customer, Order> o = c.join(Customer__.orders);
cq.select(c).distinct(true);
Subquery<Double> sq = cq.subquery(Double.class);
Root<Order> subo = cq.correlate(o);
sq.select(cb.max(subo.get(Order_.totalPrice)));
cq.where(cb.equal(o.get(Order_.totalPrice), cb.all(sq)));

정답: C

문제5
A developer wants to write a type-safe Criteria API query. Which two of the following statements true about Criteria query roots? (Choose two)

A. The query may define multiple query roots.

B. The query MUST define a query root.

C. The query MUST NOT define multiple query roots.

D. The query MUST define a query root only if it navigates to related entities.

정답: C,D

설명: (KoreaDumps 회원만 볼 수 있음)

문제6
A user entity is in a one-to-many relationship with a Book entity. In other words, a developer reach the collection of books that a user instance myUser has by using the path expression-"myuser books".
A developer wants to write a Java Persistence query that returns all users that have only two books.
Which two are valid queries that return this information? (Choose two.)

A. SELECT u FROM User u (WHERE COUNT (b) FROM u.books b) = 2

B. SELECT u FROM User WHERE COUNT (u.books) = 2

C. SELECT u FROM User U WHERE SIZE (u.books) = 2

D. SELECT u FROM user u WHERE (SELECT SIZE (b) FROM u.books b) = 2

정답: A,C

문제7
If a Persistence application locks entity x with a pessimistic lock, which statement is true?

A. The Persistentprovider will lock the database row(s) that correspond to all persistent fields of properties of an instance, including element collections.

B. A Persistence provider will lock the entity relationships for which the locked entity contains the foreign key.

C. Only single table per class hierarchy mapping is supported with this lock type.

D. A separate lock statement must be called for each subclass in entity hierarchy.

정답: B

설명: (KoreaDumps 회원만 볼 수 있음)

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