📝 Quiz – JPA and Hibernate

This quiz will help you evaluate your understanding of JPA and Hibernate.

👉 Attempt all questions without referring to notes.

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🧠 Section 1: Conceptual Questions

Q1. What is ORM? Why is it used?

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Q2. What is the difference between JPA and Hibernate?

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Q3. What does @Entity annotation do?

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Q4. What is the purpose of @Id and @GeneratedValue?

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Q5. What is the role of JpaRepository?

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Q6. What is the difference between save() and saveAndFlush()?

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Q7. What is FetchType.LAZY?

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Q8. When should you avoid using EAGER fetching?

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Q9. What is a transaction? Why is it important?

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Q10. Why should controllers not directly access repositories?

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💻 Section 2: Code Understanding

Q11. What will happen when this code runs?

@Entity
public class Student {
    @Id
    private Long id;
    private String name;
}

👉 What is missing here?

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Q12. Identify the issue:

@OneToMany
private List<Course> courses;

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Q13. What is wrong with this mapping?

@ManyToOne
private Student student;

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Q14. Predict the issue:

@OneToMany(fetch = FetchType.LAZY)
private List<Course> courses;

Accessed outside service layer.

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Q15. What does this method do?

List<Student> findByEmailContaining(String keyword);

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🧩 Section 3: Scenario-Based Questions

Q16. You are fetching a Student and its Courses, but performance is slow. What could be the issue?

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Q17. You get a LazyInitializationException. Why does it occur?

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Q18. You need to store multiple courses for a student. Which relationship will you use?

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Q19. You want to ensure email is always valid before saving. What will you do?

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Q20. Your API is exposing database entities directly. Why is this a bad practice?

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🔍 Section 4: Debug Thinking

Q21. Your application is not creating tables automatically. What could be wrong?

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Q22. Data is not saving in database even after calling save(). What could be the issue?

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Q23. Duplicate records are being inserted. What might be missing?

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Q24. You are seeing too many SQL queries in logs. What problem is this?

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Q25. Your API crashes when fetching relationships. What should you check?

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🧠 Self-Evaluation

After completing the quiz:

• Did you understand relationships clearly?
• Can you explain LAZY vs EAGER confidently?
• Are you comfortable with repositories?
• Can you debug common JPA issues?

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🚀 Next Step

Proceed to:

👉 Assignment

This is where you apply everything in a real backend scenario.

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🔥 Why this quiz is strong

• Covers concept + code + real-world issues
• Includes debugging mindset (critical for backend engineers)
• Prepares her for real project work
• Identifies weak areas before assignment

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