SQL错误：1452,SQLSTATE:23000无法添加或更新子行：外键约束失败

Question

@Override
public boolean addProfile(User user) {
    UserRole userRole = new UserRole();
    userRole.setRole("ROLE_USER");
    userRole.setUser(user);

    boolean status = false;
    try {
        this.sessionFactory.getCurrentSession().save(user);
        this.sessionFactory.getCurrentSession().save(userRole); //getting exception here
        status = true;

保存UserRole时出现以下异常。this.sessionFactory.getCurrentSession().save(userRole)；

例外

调试:org.hibernate.engine.jdbc.spi.sqlExceptionHelper-无法执行语句[n/a]com.mysql.jdbc.exceptions.mysqlintegrityConstraintViolationException：无法添加或更新子行：外键约束失败(mydb。user_role，约束fk_user_user_role_username)外键(username)引用

警告：org.hibernate.engine.jdbc.spi.sqlExceptionHelper-SQL错误：1452,SQLState：23000错误：org.hibernate.engine.jdbc.spi.sqlExceptionHelper-无法添加或更新子行：外键约束失败(mydb。user_role,约束fk_user_user_role_username)外键(username)引用user(异常：无法执行语句debug：org.hibernate.engine.transaction.spi.AbstractTransactionImpl-提交

用户表

user_id int(11) NO  PRI     auto_increment
username    varchar(100)    NO  UNI     
password    varchar(60) NO  

user_role表

user_role_id    int(11) NO  PRI     auto_increment
username    varchar(100)    NO  MUL     
role    varchar(45) NO  

user.java

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "user_id", unique = true, nullable = false)
private String userId;

@Column(name = "USERNAME", unique = true, nullable = false, length = 100)
private String username;

userrole.java

@Entity
@Table(name = "user_role", catalog = "mydb", uniqueConstraints = @UniqueConstraint(columnNames = {
        "role", "username" }))
public class UserRole {
@Id
@GeneratedValue(strategy = IDENTITY)
@Column(name = "user_role_id", unique = true, nullable = false)
private Integer userRoleId;

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "username", nullable = false)
private User user;

@Column(name = "role", nullable = false, length = 45)
private String role;




Answer 1

我找到了解决办法

因为我映射了一个指向唯一键的外键。我们需要告诉Hibernate您所引用的用户列（如果它不是主键的话）。为此，我们必须在第二个实体中添加referencedColumnName：

为了解决这个问题，我在userrole.java中添加了referencedColumnName=“username”

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "username", nullable = false, referencedColumnName = "username")
private User user;