3
我的域模型圖如下所示： 
JPA引用完整性約束違規一對多和批量操作查詢
正如你可以看到我有學生和考勤之間和考勤和研討會之間的一對多releation。
下面是學生和考勤班，以及我的助手班（初始化者）。
package com.seminars.domain;
import java.util.Calendar;
import java.util.HashSet;
import java.util.Set;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import org.hibernate.annotations.GenericGenerator;
import com.seminars.util.SimpleCalendar;
@Entity
@Table(name="Student")
public class Student {
/*start all class fields*/
@Id
//@GenericGenerator(name="kaugen" , strategy="increment")
//@GeneratedValue(generator="kaugen")
@Column(name="studentId")
//@GeneratedValue(strategy=GenerationType.AUTO)
private int studentId;
@Column(name="firstname", length=50, nullable = false)
private String firstname;
@Column(name="lastname", length=50, nullable = false)
private String lastname;
@Column(name="email", length=50, nullable = false)
private String email;
@Column(name="username", length=50, nullable = false)
private String username;
@Column(name="password", length=50, nullable = false)
private String password;
@Column(name="idCard", length=50, nullable = false)
private String idCard;
/* end fields*/
@OneToMany(mappedBy = "student",cascade=CascadeType.ALL)
private Set<Attendance> attendance = new HashSet<Attendance>() ;
/**
* default constructor
*/
public Student(){
}
/**
* Secondary Constructor to automatically create a Student
* @param firstname
* @param lastname
* @param email
* @param username
* @param password
* @param idcard
*/
public Student(String firstname,String lastname,String email, String username,String password, String idcard){
this.setFirstname(firstname);
this.setLastname(lastname);
this.setEmail(email);
this.setIdCard(idcard);
this.setPassword(password);
this.setUsername(username);
}
public int getStudentId() {
return studentId;
}
public void setStudentId(int studentId) {
this.studentId = studentId;
}
public String getFirstname() {
return firstname;
}
public void setFirstname(String firstname) {
this.firstname = firstname;
}
public String getLastname() {
return lastname;
}
public void setLastname(String lastname) {
this.lastname = lastname;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getIdCard() {
return idCard;
}
public void setIdCard(String idCard) {
this.idCard = idCard;
}
/*Methods for connecting Student<------->Attendance*/
/**
* @return a new hashset contain
* <p>all attendances of the student
*/
public HashSet<Attendance> getAttendance(){
return new HashSet<Attendance>(attendance);
}
/**
* @param attendance
* @param seminar
*/
public void addAttendance(Attendance attendance, Seminar seminar){
if(attendance!=null & seminar!=null){
attendance.setStudent(this);
attendance.setSeminar(seminar);
attendance.setRegisterDate((new SimpleCalendar(Calendar.getInstance()))); /* xreiazomaste na orizete I timi apo to sistima automata*/
}
}
/**
* @param attendance to remove from HashSet
*/
public void removeAttendance(Attendance attendance){
attendance.setStudent(null);
}
/**
* @return Attendance HashSet
*/
public Set<Attendance> findAttendance(){
return attendance;
}
/* (non-Javadoc)
* @see java.lang.Object#equals(java.lang.Object)
*/
public boolean equals(Object other) {
if (other == null) {
return false;
}
if (this == other) {
return true;
}
if (! (other instanceof Student)) {
return false;
}
Student theStudent = (Student) other;
//Integer a=getStudentId();
//Integer b=theStudent.getStudentId();
if(!(getIdCard()==null) ? theStudent.getIdCard()==null : getIdCard().equals(theStudent.getIdCard())){
return false;
}
return true;
}
/* (non-Javadoc)
* @see java.lang.Object#hashCode()
*/
public int hashCode() {
return idCard == null ? 0 : idCard.hashCode();
}
}
考勤類
/**
*
*/
package com.seminars.domain;
import java.util.Calendar;
import java.util.HashSet;
import java.util.Set;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
import org.junit.Assert;
import org.junit.Test;
import com.seminars.util.SimpleCalendar;
/**
* @author Ilias
*
*/
@Entity
@Table(name = "Attendance")
public class Attendance {
public Attendance() {
this.registerDate=new SimpleCalendar(Calendar.getInstance());
}
@Id
@Column(name="attendanceId")
@GeneratedValue(strategy=GenerationType.AUTO)
private int attendanceId;
@Column(name = "registerDate", length = 200, nullable = false)
//@Temporal(TemporalType.DATE)
@org.hibernate.annotations.Type(
type="com.seminars.persistence.SimpleCalendarCustomType")
private SimpleCalendar registerDate;
@Column(name = "success")
private boolean success;
@ManyToOne
@JoinColumn(name="studentId", nullable = false)
private Student student;
@OneToMany(mappedBy = "attendance",cascade=CascadeType.ALL)
private Set<Absence> absence = new HashSet<Absence>() ;
@ManyToOne
@JoinColumn(name="seminarId", nullable = false)
private Seminar seminar;
@OneToMany(mappedBy = "attendance",cascade=CascadeType.ALL)
private Set<Payment> payment = new HashSet<Payment>() ;/*<<<*/
public SimpleCalendar getRegisterDate() {
return registerDate;
}
public void setRegisterDate(SimpleCalendar registerDate) {
this.registerDate = registerDate;
}
public boolean isSuccess() {
return success;
}
public void setSuccess(boolean success) {
this.success = success;
}
/**
* @return the student
*/
public Student getStudent() {
return student;
}
/**
* @param student the student to set
*/
public void setStudent(Student student) {
//this.student = student.findAttendance().add(this);
if (this.student != null) {
this.student.findAttendance().remove(this);
}
this.student = student;
if (this.student != null) {
this.student.findAttendance().add(this);
}
}
/**
* @return the seminar
*/
public Seminar getSeminar() {
return seminar;
}
/**
* @param seminar the seminar to set
*/
public void setSeminar(Seminar seminar) {
//this.student = student.findAttendance().add(this);
if (this.seminar != null) {
this.seminar.findAttendance().remove(this);
}
this.seminar = seminar;
if (this.seminar != null) {
this.seminar.findAttendance().add(this);
}
}
public HashSet<Absence> getAbsence(){
return new HashSet<Absence>(absence);
}
public void addAbsence(Absence absence, SimpleCalendar date){
if(absence!=null && date!=null){
absence.setAttendance(this);
/*stelnoume tin imerominia pou kataxorei I gramamteia oti elipe o foititis*/
absence.setDate(date);
}
}
/**
* @return Absence HashSet
*/
public Set<Absence> findAbsence(){
return absence;
}
/**
* @return HashSet<Payment>
*/
public HashSet<Payment> getPayment(){
return new HashSet<Payment>(payment);
}
public void addPayment(Payment payment, SimpleCalendar date){
if(payment!=null && date!=null){
payment.setAttendance(this);
/*stelnoume tin imerominia pou kataxorei I gramamteia oti elipe o foititis*/
//absence.setDate(date);
}
}
/**
* @return Payment HashSet
*/
public Set<Payment> findPayment(){
return payment;
}
/* (non-Javadoc)
* @see java.lang.Object#equals(java.lang.Object)
*/
@Override
public boolean equals(Object other) {
if (other == null) {
return false;
}
if (this == other) {
return true;
}
if (! (other instanceof Attendance)) {
return false;
}
Attendance theAttendance = (Attendance) other;
//Integer a=getStudentId();
//Integer b=theStudent.getStudentId();
if(!(getStudent()==null) ? theAttendance.getStudent()==null : getStudent().equals(theAttendance.getStudent())){
return false;
}
if(!(getSeminar()==null) ? theAttendance.getSeminar()==null : getSeminar().equals(theAttendance.getSeminar())){
return false;
}
return true;
}
/* (non-Javadoc)
* @see java.lang.Object#hashCode()
*/
public int hashCode() {
if(student==null && seminar==null){
return 0;
}
else {
int result=0;
if(student!=null)
result+= 13*getStudent().hashCode()/*+getSeminar().hashCode()*/;
if(seminar!=null)
result+= 13*getSeminar().hashCode();
return result;
}
/*int result = 0;
result = getStudent() == null ? result : 13 * result + getStudent().hashCode();
result = getSeminar() == null ? result : 13 * result + getSeminar().hashCode();
return result; */
}
}
初始化器類
package com.seminars.persistence;
import java.util.Calendar;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;
import javax.persistence.Query;
import com.seminars.domain.Attendance;
import com.seminars.domain.Seminar;
import com.seminars.domain.Student;
import com.seminars.util.SimpleCalendar;
public class Initializer {
/* EntityManager em = DatabaseFactory.createEntityManager();
EntityTransaction tx = em.getTransaction();*/
//delete all data from database
public void eraseData() {
EntityManager em = DatabaseFactory.getCurrentEntityManager();
EntityTransaction tx = em.getTransaction();
tx.begin();
Query query = em.createNativeQuery("delete from \"Student\"");
query.executeUpdate();
query = em.createNativeQuery("delete from \"Absence\"");
query.executeUpdate();
query = em.createNativeQuery("delete from \"Attendance\"");
query.executeUpdate();
query = em.createNativeQuery("delete from \"Payment\"");
query.executeUpdate();
query = em.createNativeQuery("delete from \"Seminar\"");
query.executeUpdate();
query = em.createNativeQuery("delete from \"Program\"");
query.executeUpdate();
tx.commit();
em.close();
}
public void prepareData() {
// πριν εισάγουμε τα δεδομένα διαγράφουμε ότι υπάρχει
eraseData();
EntityManager em = DatabaseFactory.createEntityManager();
EntityTransaction tx = em.getTransaction();
tx.begin();
Student s1=new Student("george","antoniou","[email protected]","antoniou","password","998456");
s1.setStudentId(1);
Student s2=new Student("ilias","butsikakis","[email protected]","ilias","butsi","98756423");
s2.setStudentId(2);
Seminar sem1=new Seminar(1, "Java", 5,500, 2, new SimpleCalendar(2013,1,5), new SimpleCalendar(2013,2,5),"100");
sem1.setSeminarId(1);
Attendance att=new Attendance();
att.setRegisterDate(new SimpleCalendar(Calendar.getInstance()));
//s1.addAttendance(att, sem1);
//s1=em.merge(s1);
//s2=em.merge(s2);
//sem1=em.merge(sem1);
//em.persist(att);
em.persist(s1);
em.persist(s2);
em.persist(sem1);
s1.addAttendance(att, sem1);
em.persist(att);
s1=em.merge(s1);
em.persist(s1);
tx.commit();
em.close();
}
/*public void prepareData1() {
// πριν εισάγουμε τα δεδομένα διαγράφουμε ότι υπάρχει
eraseData();
Student s1=new Student("george","antoniou","[email protected]","antoniou","password","998456");
s1.setStudentId(1);
Student s2=new Student("ilias","butsikakis","[email protected]","ilias","butsi","98756423");
s2.setStudentId(2);
Seminar sem1=new Seminar(1, "Java", 5,500, 2, new SimpleCalendar(2013,1,5), new SimpleCalendar(2013,2,5),"100");
//EntityManager em = DatabaseFactory.createEntityManager();
EntityManager em = DatabaseFactory.createEntityManager();
EntityTransaction tx = em.getTransaction();
tx.begin();
em.persist(s1);
em.persist(s2);
tx.commit();
em.close();
/*NOTE ALWAYS REMEMBER:
* 1)Open entity Manager,
* 2)Open Transaction
* 3)Create Items
* else You will need to use merge or you will get a detached exception!!!
* */
//s1=em.merge(s1);
/* Student s1=new Student("george","antoniou","[email protected]ail.com","antoniou","password","998456");
s1.setStudentId(1);
Student s2=new Student("ilias","butsikakis","[email protected]","ilias","butsi","98756423");
s2.setStudentId(2);
Seminar sem1=new Seminar(1, "Java", 5,500, 2, new SimpleCalendar(2013,1,5), new SimpleCalendar(2013,2,5),"100");
s1=em.merge(s1);
s2=em.merge(s2);
sem1=em.merge(sem1);
em.persist(s1);
em.persist(s2);
em.persist(sem1);
tx.commit();
em.close();*/
/*EntityManagerFactory emf = Persistence.createEntityManagerFactory("library");
EntityManager em = emf.createEntityManager();*/
//}
}
該項目主要是通過JUnit測試檢查，因此在初始化器類，我們有這產生了一些樣本數據使用PrepareData方法在每次檢查中還有一個刪除方法，以確保每次檢查都使用相同的數據完成。
在試圖檢查Student和Attendance之間的連接之前，一切似乎都正常。我在初始化器中創建了一個新的考勤對象，以測試學生是否可以在研討會中註冊「好」，並且我收到了很多異常消息。
我注意到大多數雖然（它顯示在控制檯）的一個是
3781 [主]錯誤org.hibernate.util.JDBCExceptionReporter - 參照完整性約束衝突：「FKE7E9BF09F9FEB38B ：「 PUBLIC」。「」出勤「」外國關鍵（學生）參考 PUBLIC。「」學生「」（「」studentId「」）「; SQL語句：從 「學生」 [23003-135]
我檢查，以確保註釋和瀑布是在正確的地方，但沒有結果刪除...
我也試過改變順序的項目都保存在initilizer類，但隨後其他錯誤出現
**javax.persistence.PersistenceException: org.hibernate.PropertyValueException: not-null property references a null or transient value: com.seminars.domain.Attendance.seminar**
at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1235)
at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1168)
at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1174)
at org.hibernate.ejb.AbstractEntityManagerImpl.persist(AbstractEntityManagerImpl.java:674)
at com.seminars.persistence.Initializer.prepareData(Initializer.java:73)
at com.seminars.services.ManageStudentServiceTest.setup(ManageStudentServiceTest.java:60)
at com.seminars.services.ManageStudentServiceTest.testManageStudentService(ManageStudentServiceTest.java:97)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:44)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:180)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:41)
at org.junit.runners.ParentRunner$1.evaluate(ParentRunner.java:173)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31)
at org.junit.runners.ParentRunner.run(ParentRunner.java:220)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: org.hibernate.PropertyValueException: not-null property references a null or transient value: com.seminars.domain.Attendance.seminar
at org.hibernate.engine.Nullability.checkNullability(Nullability.java:101)
at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:313)
at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:204)
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:130)
at org.hibernate.ejb.event.EJB3PersistEventListener.saveWithGeneratedId(EJB3PersistEventListener.java:69)
at org.hibernate.event.def.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:179)
at org.hibernate.event.def.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:135)
at org.hibernate.event.def.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:61)
at org.hibernate.impl.SessionImpl.firePersist(SessionImpl.java:800)
at org.hibernate.impl.SessionImpl.persist(SessionImpl.java:774)
at org.hibernate.impl.SessionImpl.persist(SessionImpl.java:778)
at org.hibernate.ejb.AbstractEntityManagerImpl.persist(AbstractEntityManagerImpl.java:668)
... 27 more
下面是在初始化類改變項目的順序才趕上來的例外列表：
> javax.persistence.PersistenceException:
> org.hibernate.exception.ConstraintViolationException: could not
> execute native bulk manipulation query at
> org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1235)
> at
> org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1168)
> at
> org.hibernate.ejb.AbstractEntityManagerImpl.throwPersistenceException(AbstractEntityManagerImpl.java:1245)
> at
> org.hibernate.ejb.AbstractQueryImpl.executeUpdate(AbstractQueryImpl.java:108)
> at
> com.seminars.persistence.Initializer.eraseData(Initializer.java:37)
> at
> com.seminars.services.ManageStudentServiceTest.empty(ManageStudentServiceTest.java:64)
> at
> com.seminars.services.ManageStudentServiceTest.testManageStudentService(ManageStudentServiceTest.java:99)
> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at
> sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at
> java.lang.reflect.Method.invoke(Unknown Source) at
> org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
> at
> org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
> at
> org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
> at
> org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
> at
> org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
> at
> org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31)
> at
> org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
> at
> org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:44)
> at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:180)
> at org.junit.runners.ParentRunner.access$000(ParentRunner.java:41)
> at org.junit.runners.ParentRunner$1.evaluate(ParentRunner.java:173)
> at
> org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
> at
> org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31)
> at org.junit.runners.ParentRunner.run(ParentRunner.java:220) at
> org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
> at
> org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
> at
> org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
> at
> org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
> at
> org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
> at
> org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
> Caused by: org.hibernate.exception.ConstraintViolationException: could
> not execute native bulk manipulation query at
> org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:96)
> at
> org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
> at
> org.hibernate.engine.query.NativeSQLQueryPlan.performExecuteUpdate(NativeSQLQueryPlan.java:219)
> at
> org.hibernate.impl.SessionImpl.executeNativeUpdate(SessionImpl.java:1300)
> at
> org.hibernate.impl.SQLQueryImpl.executeUpdate(SQLQueryImpl.java:365)
> at
> org.hibernate.ejb.QueryImpl.internalExecuteUpdate(QueryImpl.java:183)
> at
> org.hibernate.ejb.AbstractQueryImpl.executeUpdate(AbstractQueryImpl.java:99)
> ... 27 more Caused by: org.h2.jdbc.JdbcSQLException: Referential
> integrity constraint violation: "FKE7E9BF09F9FEB38B:
> PUBLIC.""Attendance"" FOREIGN KEY(STUDENT) REFERENCES
> PUBLIC.""Student""(""studentId"")"; SQL statement: delete from
> "Student" [23003-135] at
> org.h2.message.DbException.getJdbcSQLException(DbException.java:327)
> at org.h2.message.DbException.get(DbException.java:167) at
> org.h2.message.DbException.get(DbException.java:144) at
> org.h2.constraint.ConstraintReferential.checkRow(ConstraintReferential.java:378)
> at
> org.h2.constraint.ConstraintReferential.checkRowRefTable(ConstraintReferential.java:395)
> at
> org.h2.constraint.ConstraintReferential.checkRow(ConstraintReferential.java:275)
> at org.h2.table.Table.fireConstraints(Table.java:788) at
> org.h2.table.Table.fireAfterRow(Table.java:805) at
> org.h2.command.dml.Delete.update(Delete.java:79) at
> org.h2.command.CommandContainer.update(CommandContainer.java:70) at
> org.h2.command.Command.executeUpdate(Command.java:199) at
> org.h2.jdbc.JdbcPreparedStatement.executeUpdateInternal(JdbcPreparedStatement.java:141)
> at
> org.h2.jdbc.JdbcPreparedStatement.executeUpdate(JdbcPreparedStatement.java:127)
> at
> org.hibernate.engine.query.NativeSQLQueryPlan.performExecuteUpdate(NativeSQLQueryPlan.java:210)
> ... 31 more
你能幫我確定爲什麼會發生這些錯誤嗎？我嘗試了所有我能想到的，但很少成功的東西。任何幫助將不勝感激。
通過在學生之前添加考勤刪除，它可以工作。 現在我有另一個小問題。當我嘗試測試出席的學生的刪除時，我得到「Entitynotfound異常：傳遞給堅持的實體」。 我修改了關係如下： 在學生： @OneToMany（orphanRemoval =假，級聯= CascadeType.ALL，的mappedBy = 「學生」） 和考勤 @ManyToOne（級聯= {CascadeType.PERSIST，CascadeType.MERGE }）\t \t @JoinColumn（name =「studentId」，nullable = false） \t私立學生學生; 你能幫我解決這個問題嗎？ – George