What is cascade delete ?

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A deletion that triggers another deletion. A cascade delete can be specified for an entity bean that has container-managed persistence.

In the context of databases and Java Persistence (JPA), cascade delete refers to the automatic deletion of related records in a database when the primary record is deleted. This feature is often used to maintain referential integrity and ensure that the database remains consistent.

For example, consider two entities in a Java application: Parent and Child, where Parent has a one-to-many relationship with Child. If cascade delete is enabled on the relationship, deleting a Parent entity will automatically trigger the deletion of its associated Child entities.

Here’s a brief explanation of how cascade delete works:

  1. Parent Entity Deletion: When you delete a Parent entity, if cascade delete is configured, the associated Child entities are also deleted.
    java
    @Entity
    public class Parent {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @OneToMany(mappedBy = "parent", cascade = CascadeType.ALL)
    private List<Child> children;

    // other fields and methods
    }

  2. Child Entity:
    java
    @Entity
    public class Child {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @ManyToOne
    @JoinColumn(name = "parent_id")
    private Parent parent;

    // other fields and methods
    }

In this example, the cascade = CascadeType.ALL attribute in the @OneToMany annotation of the Parent entity indicates that all operations (including delete) should be cascaded to the associated Child entities.

It’s important to use cascade delete cautiously, as it can lead to unintended data loss if not handled properly. The choice of whether to use cascade delete depends on the specific requirements of your application and the relationships between entities.