What's the difference between @JoinColumn and mappedBy when using a JPA @OneToMany association

Question

What is the difference between:

@Entity
public class Company {

    @OneToMany(cascade = CascadeType.ALL , fetch = FetchType.LAZY)
    @JoinColumn(name = \"c         


        

Answer 1

I'd just like to add that @JoinColumn does not always have to be related to the physical information location as this answer suggests. You can combine @JoinColumn with @OneToMany even if the parent table has no table data pointing to the child table.

How to define unidirectional OneToMany relationship in JPA

Unidirectional OneToMany, No Inverse ManyToOne, No Join Table

It seems to only be available in JPA 2.x+ though. It's useful for situations where you want the child class to just contain the ID of the parent, not a full on reference.