How to become a Java Champion
1515 days That’s how much time it took me from the moment I started this blog until I became a Java Champion. In this article, I’m going to show you what I did so that, after 1515 days, I became the first Java Champion from Romania.
How to map a JPA @ManyToOne relationship to a SQL query using the Hibernate @JoinFormula annotation
Introduction Someone asked me to answer the following StackOverflow question, and, because the question is very interesting from an SQL perspective, I decided to turn the answer it into a blog post. In this article, we are going to see how to map a JPA @ManyToOne association to the result of a SQL query using the Hibernate-specific @JoinFormula annotation.
How to emulate @CreatedBy and @LastModifiedBy from Spring Data using the @GeneratorType Hibernate annotation
Introduction Hibernate comes with many additions to the standard JPA specification. One such example is the @GeneratorType annotation which allows you to customize the way a given entity property value is automatically generated. If you’re using Spring Data, you can simply use the @CreatedBy and @LastModifiedBy annotations and the annotated entity properties are going to be populated with the currently logged user. If you’re not using Spring Data, then you can easily emulate the same behavior using the Hibernate-specific @GeneratorType annotation and the ValueGenerator callback mechanism.
How to inherit properties from a base class entity using @MappedSuperclass with JPA and Hibernate
Introduction In this article, we are going to see how @MappedSuperclass can help us reuse the @Id mapping of a JPA and Hibernate entity so that it won’t have to be declared on each and every entity.
How do UPSERT and MERGE work in Oracle, SQL Server, PostgreSQL and MySQL
Introduction Last week, Burkhard Graves asked me to answer the following StackOverflow question: And, since he wasn’t convinced about my answer: I decided to turn it into a dedicated article and explain how UPSERT and MERGE work in the top 4 most common relational database systems: Oracle, SQL Server, PostgreSQL, and MySQL.
