Why Does JPA Sometimes Ignore the @Column Annotation in Spring Boot?

Understanding Column Annotation Overriding in Spring Boot JPA

Spring Boot JPA, a popular ORM framework, allows developers to annotate entities with @Column to specify specific column names in the database. However, it has been observed that in certain scenarios, JPA might ignore the @Column annotation and default to the underscore-cased version of the property name in the database schema.

Why JPA May Ignore Column Annotation

One possible reason for JPA ignoring the @Column annotation could be the naming strategy used by the underlying Hibernate framework. By default, Hibernate uses the org.hibernate.cfg.ImprovedNamingStrategy strategy, which generates Snake Case column names regardless of the @Column annotation.

Solution: EJB3 Naming Strategy

To resolve this issue and ensure that JPA respects the @Column annotation, you can explicitly set the Hibernate naming strategy to org.hibernate.cfg.EJB3NamingStrategy. This strategy will preserve the case and character spacing specified in the @Column annotation.

SQL Server Dialect Considerations

If you are connecting to Microsoft SQL Server, you may encounter a different issue where Hibernate uses the org.hibernate.dialect.SQLServerDialect dialect. This dialect can lead to naming inconsistency, where JPA might use mixed case column names, even with the EJB3 naming strategy.

Legacy Implicit and Physical Naming Strategies

To address this issue, you can add the following properties to your application.properties file:

<code class="properties">spring.jpa.hibernate.naming.implicit-strategy=org.hibernate.boot.model.naming.ImplicitNamingStrategyLegacyJpaImpl
spring.jpa.hibernate.naming.physical-strategy=org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl</code>

These settings will force Hibernate to use the Legacy Implicit and Standard Physical naming strategies, which will ensure that the @Column annotation is respected, and column names are generated consistently.

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