Hibernate / Hibernate Interview Questions III
Explain Formula annotation in Hibernate.
@Formula annotation is used to calculate a given entity attribute using an SQL query expression. It defines a formula (derived value) which is a SQL fragment that acts as a @Column alternative in most cases. It represents read-only state.
@Entity @Table(name="area") public class Area implements Serializable { private static final long serialVersionUID = 1L; @Id @Column(name="id") private int id; @Column(name="length") private int length; @Column(name="width") private int width; @Formula(" length * width ") public long area; ... }
In the example, area property value is calculated using the length and the width properties.
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