Java code database updating
You’re going to learn about annotations in this guide, but if you want to have a look at the legacy XML mappings, have a look at this link for example.That let’s Hibernate know you have one User.class, which has annotations (most importantly, the @Entity annotation) that tell Hibernate HOW to map that class automatically to an appropriate database table.As always, however, it is very important to understand the basics, as every other option builds ON TOP of those basics.So make sure not to skip the very next section, if you are unsure about some of the mentioned concepts.You can use this guide to discover, understand, and select the right Java library to access a database, like My SQL, Postgres, Oracle - or any other one.Read this guide to understand which database library makes sense for your project and development team.Additionally, because you are a good developer, you also should make sure to close the Prepared Statement and/or connection explicitly, instead of hoping for it to be closed automatically (JDBC driver implementation dependent) later on in your code - and release any database resources along with that.
If you have the misfortune of being on Android or Java 6 or below, you can use Guava’s Closer to achieve code almost as clean with regard to resource management.Hibernate will then convert these HQL statements to proper, database specific SQL statements.In addition to HQL, Hibernate offers another query language through the Criteria API, a type-safe, programmatic API.So no matter what Java database library you are going to use in your project, you’ll need to go to the database’s website or a maven repository, fetch the latest JDBC driver and add it to your project.
Opening up and closing database connections takes some time.
However, it is a bit trickier to setup, as your project needs an annotation processing plugin to generate a "Static Metamodel" of your annotated classes and the API itself also feels a bit cumbersome to use.