Join fetch for optimization in Spring Boot - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to fetch associated entities eagerly using join fetch.

Spring Boot

String jpql = "SELECT p FROM Product p [1] p.category";

Drag options to blanks, or click blank then click option'

Afetch join

Bleft join

Cjoin fetch

Dinner join

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'left join' without 'fetch' does not fetch associations eagerly.

Using 'fetch join' alone is not valid JPQL syntax.

Using 'join fetch' in JPQL tells Hibernate to fetch the associated entity eagerly in one query.

2fill in blank

medium

Complete the JPQL query to fetch orders with their items eagerly.

Spring Boot

String jpql = "SELECT o FROM Order o [1] o.items";

Drag options to blanks, or click blank then click option'

Aleft join

Bfetch

Cinner join

Djoin fetch

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'left join' without 'fetch' only joins but does not fetch eagerly.

Using 'fetch' alone is not valid JPQL syntax.

The 'join fetch' keyword fetches the collection 'items' eagerly with the orders.

3fill in blank

hard

Fix the error in the JPQL query to fetch customers with their addresses eagerly.

Spring Boot

String jpql = "SELECT c FROM Customer c [1] c.addresses";

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Aleft join fetch

Bjoin fetch

Cfetch join

Djoin

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'join fetch' excludes customers without addresses.

Using 'fetch join' is invalid syntax.

Using 'left join fetch' fetches the addresses eagerly and includes customers without addresses.

4fill in blank

hard

Fill both blanks to create a JPQL query that fetches books with authors eagerly and orders by title.

Spring Boot

String jpql = "SELECT b FROM Book b [1] b.authors ORDER BY b.[2]";

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Ajoin fetch

Btitle

Cname

Dleft join

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'left join' without fetch does not eagerly load authors.

Ordering by 'name' orders by author name, not book title.

We use 'join fetch' to eagerly load authors and order by the book's title.

5fill in blank

hard

Fill all three blanks to write a JPQL query fetching employees with departments eagerly and filtering by department name.

Spring Boot

String jpql = "SELECT e FROM Employee e [1] e.department WHERE e.department.[2] = :[3]";

Drag options to blanks, or click blank then click option'

Ajoin fetch

Bname

CdeptName

Dleft join

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'left join' without fetch does not eagerly load departments.

Using wrong property names causes runtime errors.

We use 'join fetch' to eagerly load departments, filter by department name property 'name', and use parameter 'deptName'.