Hibernate Tips is a series of posts in which I describe a quick and easy solution for common Hibernate questions. If you have a question for a future Hibernate Tip, please post a comment below. Question: One of the readers of my article about using Hibernate with a MySQL database asked the following question: What is…
Hibernate Tips is a series of posts in which I describe a quick and easy solution for common Hibernate questions. If you have a question for a future Hibernate Tip, please post a comment below. Question: I modeled a one-to-one association and activated lazy loading for it. But it doesn’t work. How do I tell…
Mapping a primary key column with JPA and Hibernate is simple. You just need to add an attribute to your entity, make sure that its type and name match the database column, annotate it with @Column and you’re done. You can then use the primary key to load the entity, and Hibernate sets the primary…
The implementation of the equals() and hashCode() methods for entity classes is an often discussed question. Do you really need them? There are lots of applications that work perfectly fine using Java’s default methods provided by the Object class. And if you need to implement them, how should you do that? Should you use all attributes…
A lot of applications use primary keys that are based on a sequence but use an additional prefix that contains semantic information. Here are some typical examples: A fixed String as a prefix followed by a sequence-based value of fixed or variable length, e.g., B_00001 or B_1 Year and month as a prefix followed by…