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Oracle

1Z0-898 · Question #25

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…

The correct answer is A. SELECT u FROM User U WHERE SIZE (u.books) = 2 C. SELECT u FROM User u (WHERE COUNT (b) FROM u.books b) = 2. A (not D):The SIZE(collection) function returns the number of elements in a specified collection. SIZE(c.languages) is evaluated to the number of languages in that collection. C: Example(the aggregate query returns a Long): Query q2 = em.createQuery( "SELECT COUNT(e) FROM…

JPQL

Question

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.)

Options

  • ASELECT u FROM User U WHERE SIZE (u.books) = 2
  • BSELECT u FROM User WHERE COUNT (u.books) = 2
  • CSELECT u FROM User u (WHERE COUNT (b) FROM u.books b) = 2
  • DSELECT u FROM user u WHERE (SELECT SIZE (b) FROM u.books b) = 2

How the community answered

(51 responses)
  • A
    80% (41)
  • B
    8% (4)
  • D
    12% (6)

Explanation

A (not D):The SIZE(collection) function returns the number of elements in a specified collection. SIZE(c.languages) is evaluated to the number of languages in that collection. C: Example(the aggregate query returns a Long): Query q2 = em.createQuery( "SELECT COUNT(e) FROM Employee e WHERE e.salary > :limit");

Topics

#SIZE function#collection queries#one-to-many#JPQL syntax

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