![]() ![]() We use SQL (Structured Query Language) to retrieve and interact with data in individual tables and across multiple tables. Programmers use foreign keys and join tables to define the relationships between entities-namely one-to-one, one-to-many, and many-to-many relationships. Entities are objects that are placed in tables where they occupy columns and rows, thereby outliving their existence in the program. Java objects in a relational database context are defined as entities. While developers today have many alternatives to the relational database, it is still widely used in small- and large-scale software development. Relational databases have existed as a means for storing program data since the 1970s. ![]() It has been updated by Matthew Tyson for the most recent versions of Java and Hibernate as of this writing. ![]() This tutorial was originally written by Steven Haines and published on JavaWorld. Most concepts can be extended to other Java persistence frameworks. Note that this tutorial uses Hibernate as the JPA provider. This two-part tutorial introduces JPA and explains how Java objects are modeled as JPA entities, how entity relationships are defined, and how to use JPA's EntityManager with the Repository pattern in your Java applications. This gives you all the basics for saving and loading application state. The Jakarta Persistence API (JPA) is a Java specification that bridges the gap between relational databases and object-oriented programming. ![]()
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