无法删除或更新父行ConstraintViolationException

问题描述

我有2个对象实体（用户和电话），他们应该有多对多的关系。

User.java

  / /所有列
 
 @ManyToMany（cascade = CascadeType.MERGE，fetch = FetchType.EAGER）
 @JoinTable（name =USER_PHONE，
 joinColumns = @JoinColumn（name = user_id，referencedColumnName =id），
 inverseJoinColumns = @JoinColumn（name =phone_id，referencedColumnName =id））
 private List< Phone>手机; 
  

Phone.java

  //所有列
 @ManyToMany（cascade = CascadeType.MERGE，fetch = FetchType.EAGER）
 @JoinTable（name =USER_PHONE，
 joinColumns = @JoinColumn（name =user_id，referencedColumnName =id））
 private List<使用者名称>用户列表; 
  

现在，我在USER表中添加2个ID为1和2的用户。
然后，我添加一个ID为1的电话，并将它们映射到用户ID（1& 2）。

我的USER_PHONE表格如下所示：

 从USER_PHONE中选择* ; 
 + ---------- + --------- + 
 | phone_id | user_id | 
 + ---------- + --------- + 
 | 1 | 1 | 
 | 1 | 2 | 
 + ---------- + --------- + 
  

现在，我想删除一个ID为2的用户。
当我尝试这样做时，出现错误

  javax.persistence.PersistenceException：org.hibernate.exception.ConstraintViolationException：无法删除或更新父行：外键约束失败（`dbname`.`USER_PHONE`，CONSTRAINT`FKC6A847DAFA96A429` FOREIGN KEY（` user_id`）参考````````
  

我的删除脚本：

  String query =DELETE User where id =？1; 
 try {
 Query q = entityManager.createQuery（query）; 
 q.setParameter（1，id）; 
 q.executeUpdate（）; 
 System.out.println（System.currentTimeMillis（）+DELETE：userId+ id +==> deleted）; 
} catch（Exception e）{
 e.printStackTrace（）; 
返回false; 
} 
  

任何想法我哪里错了？
非常感谢:)

解决方案

尝试使用 entityManager.createNativeQuery（）。您不能使用 createQuery（），因为表应该作为Java代码中的一个实体出现。此外，您需要使用确切的SQL格式。

String query =DELETE FROM USER_PHONE WHERE user_id =？1;
$ pre $ {
Query q = entityManager.createNativeQuery（query）;
q.setParameter（1，id）;
q.executeUpdate（）;
System.out.println（System.currentTimeMillis（）+DELETE User_Phone：userId+ id +==> deleted）;
} catch（Exception e）{
e.printStackTrace（）;
返回false;

$ / code> c $ c>（使用 createNativeQuery（）），然后从 User （使用 createQuery （））

I have 2 object entities (User and Phone) and they are supposed to have many-to-many relations.

User.java

//all columns

@ManyToMany(cascade = CascadeType.MERGE, fetch = FetchType.EAGER)
    @JoinTable(name = "USER_PHONE",
            joinColumns = @JoinColumn(name = "user_id", referencedColumnName = "id"),
            inverseJoinColumns = @JoinColumn(name = "phone_id", referencedColumnName = "id"))
    private List<Phone> phones;

Phone.java

//all columns
@ManyToMany(cascade = CascadeType.MERGE, fetch = FetchType.EAGER)
    @JoinTable(name = "USER_PHONE",
            joinColumns = @JoinColumn(name = "phone_id", referencedColumnName = "id"),
            inverseJoinColumns = @JoinColumn(name = "user_id", referencedColumnName = "id"))
    private List<User> userList;

Now, I add 2 users with IDs 1 and 2 in my USER table.Then, I add a single phone with id 1 and map them to both the user IDs(1&2) .

My USER_PHONE table looks as below:

Select * from USER_PHONE;
+----------+---------+
| phone_id | user_id |
+----------+---------+
|        1 |       1 |
|        1 |       2 |
+----------+---------+

Now, I wish to remove a user with ID 2.When I try to do this, I get an error

javax.persistence.PersistenceException: org.hibernate.exception.ConstraintViolationException: Cannot delete or update a parent row: a foreign key constraint fails (`dbname`.`USER_PHONE`, CONSTRAINT `FKC6A847DAFA96A429` FOREIGN KEY (`user_id`) REFERENCES `USER` (`ID`))

My delete script:

  String query = "DELETE User where id=?1";
        try{
            Query q = entityManager.createQuery(query);
            q.setParameter(1,id);
            q.executeUpdate();
            System.out.println(System.currentTimeMillis() + " DELETE: userId " + id + " ==> deleted");
        } catch(Exception e){
            e.printStackTrace();
            return false;
        }

Any idea where am I going wrong ?Thanks a lot :)

解决方案

Try using entityManager.createNativeQuery(). You cannot use createQuery() because the table should be present as an entity in your Java code. Also, you need to use the exact SQL format.

String query = "DELETE FROM USER_PHONE WHERE user_id=?1";

    try{
        Query q = entityManager.createNativeQuery(query);
        q.setParameter(1,id);
        q.executeUpdate();
        System.out.println(System.currentTimeMillis() + " DELETE User_Phone: userId " + id + " ==> deleted");
    } catch(Exception e){
        e.printStackTrace();
        return false;
    }`

First delete the row from USER_PHONE (using createNativeQuery()), and then from User (using createQuery())

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