@Entity

@OneToMany Defines a many-vaued association with one-to-many multiplicity

@ManyToOne Defines a single-valued association to another entity class that has many-to-one multiplicity

@OneToMany Defines a single-valued association to another entity class that has one-to-many multiplicity

@ManyToMany defines a many-valued association with many-to-many multiplicity

mappedBy references the field that owns the relationship in the referenced entity. This is generally required.

EAGER - loads all related objects immediately

LAZY - loads the related objects only if they are accessed for the first time

• One2Many

• Many2Many

The master branch is the default project which is the same as Many2Many. It illustrates how to create a ManyToMany relationship where one pet has many owners and each owner can own many pets.

The One2Many branch illusrates how to work around the complications of the Many2Many relationship by creating two one2many relationships.

use git checkout One2Many to checkout that branch and observe how the project changes when designing the database this way.