Master Hibernate and JPA with Spring Boot in 100 Steps - Step 47 - JPA Inheritance Hierarchies and Mappings-Joined

The video tutorial explains the 'table per class' inheritance strategy in database design, where each subclass has its own table, and a join is performed to retrieve subclass details. The tutorial demonstrates this with an example using an H2 console, showing how tables for employees, full-time employees, and part-time employees are structured and queried. It highlights the benefits of avoiding column duplication but notes the performance cost due to multiple joins. The tutorial concludes by summarizing the strategy's advantages and limitations, setting the stage for exploring other options in future lessons.

What is the main purpose of using a 'table per class' strategy in database design?

• To store all data in a single table

• To map fields specific to subclasses to separate tables

• To avoid using any joins in queries

• To duplicate columns across multiple tables

In the practical application, what is the role of the ID in the full-time employee table?

• It is only a foreign key

• It serves as both a primary key and a foreign key

• It is only a primary key

• It is not used in the full-time employee table

What is a potential downside of using joins in database design?

• Simplified query structure

• Increased data redundancy

• Improved performance

• Complex queries and potential performance issues

How many tables are joined to retrieve the complete employee details in the example?

• Three tables

• One table

• Four tables

• Two tables

What is a benefit of the 'joined' option in terms of database design?

• Increased complexity

• No duplication of columns

• No need for joins

• Duplication of columns