In a comment here on the blog, Mehmet asked how he could call a function before inserting or updating an entity in the database. There are several ways you can call a function as part of an SQL INSERT or UPDATE statement. But these are not your only options. To change an attribute’s value before…
Most databases put a lot of effort into analyzing SQL statements and finding the optimal execution plan. This often makes the difference between a slow and a blazing fast statement. But this analysis can also be rather complex. That’s why a lot of databases try to cache and reuse the created execution plans. Hibernate and…
Arrays are a common data type in Java and part of the SQL-99 standard. So, it should be easy and quite common to use them with Hibernate, right? No, they aren’t. Most developers try to avoid using arrays in their persistence layers. There are several reasons for that: Not all DBMS support arrays. Because of…
When you model a hierarchical data structure, you often have to use self-referencing associations. Both ends of these associations are of the same type. In other words, the entity object on which the association is defined and the one the association references are of the same type. In your database, you model that using a…
The entity lifecycle model is one of the core concepts of JPA and all its implementations. Even though it’s not directly visible when working with JPA’s EntityManager, it affects all operations you perform. The different states of the model define how your persistence provider, e.g. Hibernate, handles your entity objects. This includes if it loads…
