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[英]JPA @ManyToMany - Cannot delete or update a parent row: a foreign key constraint fails
[英]ManyToMany - Cannot delete or update a parent row: a foreign key constraint fails (JAVA SPRING)
我將兩列合並為一列,現在當我嘗試刪除一些 ethintent 時,Topic 向我拋出了這個錯誤。 該更新對我有用,沒有任何問題。
我如何加入專欄:
@ManyToMany(cascade = CascadeType.ALL, fetch=FetchType.LAZY)
@JoinTable(name = "subjects_topic", joinColumns = @JoinColumn(name = "subject_id"), inverseJoinColumns = @JoinColumn(name = "topic_id"))
@Valid
private Set<Topic> topic = new HashSet<>();
我得到的錯誤:
topic
:無法刪除或更新父行:外鍵約束失敗(lms-database
id
topic_id
subjects_topic
FKth8x407ityv1phgulkcqnlsmd
)
您可以嘗試像這樣編寫主題實體
@Entity
public class Subject{
@ManyToMany(cascade =CascadeType.ALL)
@JoinTable(name = "subjects_topic", joinColumns = @JoinColumn(name = "subject_id"), inverseJoinColumns = @JoinColumn(name = "topic_id"))
private Set<Topic> topic = new HashSet<>();
}
並像寫Topicentity一樣
@Entity
public class Topic{
@ManyToMany(mappedBy = "topic", cascade = CascadeType.All)
private Set<Subject> subject= new HashSet<>();
}
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