Andrea Boriero ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=557058%... ) *commented* on HHH-16448 ( https://hibernate.atlassian.net/browse/HHH-16448?atlOrigin=eyJpIjoiNjY4Ym... ) Re: After upgrading to Hibernate 6.2.0.Final, the unique attribute of `@JoinColumn` always behaves as true. ( https://hibernate.atlassian.net/browse/HHH-16448?atlOrigin=eyJpIjoiNjY4Ym... ) it’s a OneToOne relationship so it is correct that the join column is unique, 1 Card ↔︎ 1 User, if the same user can have multiple cards than the association should be a ManyToOne and in that case you will see that the column used as foreign key is not unique. For @Entity(name = "MembershipCard") public static class MembershipCard { @Id @Column(name = "card_number") private String number; @ManyToOne @JoinColumn(name = "user_email") private Student owner; private boolean enabled; } @Entity(name = "Student") public static class Student { @Id private String email; private String name; } Hibernate generates create table MembershipCard ( card_number varchar(255) not null, enabled boolean not null, user_email varchar(255), primary key (card_number) ) ( https://hibernate.atlassian.net/browse/HHH-16448#add-comment?atlOrigin=ey... ) Add Comment ( https://hibernate.atlassian.net/browse/HHH-16448#add-comment?atlOrigin=ey... ) Get Jira notifications on your phone! Download the Jira Cloud app for Android ( https://play.google.com/store/apps/details?id=com.atlassian.android.jira.... ) or iOS ( https://itunes.apple.com/app/apple-store/id1006972087?pt=696495&ct=Em... ) This message was sent by Atlassian Jira (v1001.0.0-SNAPSHOT#100221- sha1:9ff53d8 )