How to find which statement failed in a JDBC Batch Update
Introduction Yesterday, my Danish friend, Flemming Harms, asked my a very interesting question related to when a JDBC batch update fails. Basically, considering we are going to group several DML statements in a batch, we need a way to tell which statement is the cause of the failure. This post is going to answer this question in more detail.
The best way to soft delete with Hibernate
Introduction Each database application is unique. While most of the time, deleting a record is the best approach, there are times when the application requirements demand that database records should never be physically deleted. So who uses this technique? For instance, StackOverflow does it for all Posts (e.g. Questions and Answers). The StackOverflow Posts table has a ClosedDate column which acts as a soft delete mechanism since it hides an Answer for all users who have less than 10k reputation. If you’re using Oracle, you can take advantage of its Flashback capabilities,… Read More
How to encrypt and decrypt data with Hibernate
Introduction Today, one of my Twitter followers sent me the following StackOverflow question, and, while answering it, I realized that it definitely deserves a post of its own. In this post, I will explain how you can encrypt and decrypt data with Hibernate.
How to map the latest child of a parent entity using Hibernate JoinFormula
Introduction In this article, I’m going to explain how the Hibernate JoinFormula annotation works and how you can use it to map the latest child of a parent entity. As previously explained, the @JoinFormula is a very awesome annotation which allows you to customize the way you join entities beyond JPA @JoinColumn capabilities.
The problem of AUTO JPA GenerationType with MySQL and Hibernate
Introduction In this post, I’ll show you why you should not rely on the AUTO GenerationType strategy if you’re using MySQL and Hibernate. As I already mentioned, you should never use the TABLE identifier generator since it does not scale properly.
The JPA EntityManager createNativeQuery is a Magic Wand
Introduction I found this very interesting question on the Hibernate forum, and, in this post, I want to demonstrate to you why native SQL queries are awesome.
How to replace the TABLE identifier generator with either SEQUENCE or IDENTITY in a portable way
Introduction As previously explained, the TABLE identifier generator does not scale, so you should avoid id. However, some enterprise applications might need to run on both MySQL (which does not support database sequences), as well as Oracle, PostgreSQL, and SQL Server 2012. This is article is going to explain how easily you can achieve this goal using the JPA mapping overriding.
Why you should never use the TABLE identifier generator with JPA and Hibernate
Introduction From a data access perspective, JPA supports two major types of identifiers: assigned generated The assigned identifiers must be manually set on every given entity prior to being persisted. For this reason, assigned identifiers are suitable for natural keys. For synthetic Primary Keys, we need to use a generated entity identifier, which is supported by JPA through the use of the @GeneratedValue annotation. There are four types of generated identifier strategies which are defined by the GenerationType enumeration: AUTO IDENTITY SEQUENCE TABLE The AUTO identifier generator strategy chooses one of the… Read More
How to map table rows to columns using SQL PIVOT or CASE expressions
Introduction While reading the wonderful SQL Antipatterns book by Bill Karwin, which is a great reference for any developer that needs to interact with a Relational Database System, I found an example where the SQL PIVOT clause would work like a charm. In this post, I’m going to explain how to transpose a ResultSet using PIVOT so that rows become columns.
