Question

我的域模型图如下所示： Domain Model Abstract

正如你所看到的，我在学生和出勤之间以及出席和研讨会之间有一个同意。

以下是学生和出勤班，以及我的助手班（初始化师）。

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();
    }





}

出勤班

/**
 * 
 */
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;  */

    }


}

初始化程序类

    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","antoniougeo@hotmail.com","antoniou","password","998456");
        s1.setStudentId(1);
        Student s2=new Student("ilias","butsikakis","ili@hotmail.com","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","antoniougeo@hotmail.com","antoniou","password","998456");
        s1.setStudentId(1);
        Student s2=new Student("ilias","butsikakis","ili@hotmail.com","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","antoniougeo@hotmail.com","antoniou","password","998456");
        s1.setStudentId(1);
        Student s2=new Student("ilias","butsikakis","ili@hotmail.com","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();*/

    //}    

}

项目主要通过JUnit测试进行检查，因此在Initializer类中我们有一个PrepareData方法，它创建一些用于每次检查的样本数据以及一个删除方法，以确保每次检查都使用相同的数据。

在尝试检查学生和出勤之间的联系之前，一切似乎都正常。我去初始化器中创建了一个新的考勤对象来测试学生是否可以在研讨会上注册“ok”，我收到了很多异常消息。

我注意到的最多（因为它显示在控制台中）是

3781 [main] ERROR org.hibernate.util.JDBCExceptionReporter - 参照完整性约束违规：“FKE7E9BF09F9FEB38B： PUBLIC。“”出勤“”外键（学生）参考 PUBLIC。“”学生“”（“”studentId“”）“; SQL语句：从中删除 “学生”[23003-135]

我检查过以确保注释和级联位于正确的位置，但没有结果......

我还尝试更改项目在initilizer类中保存的顺序，但随后出现了其他错误

**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

下面是更改初始化程序类中项目顺序之前出现的异常列表：

> 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

你能帮我确定一下这些错误发生的原因吗？我尝试了所有我能想到但却收效甚微的东西。任何帮助将不胜感激。

Answer 1

您尝试在删除考勤之前删除数据库中的所有学生。但是出勤对学生来说是一把外键。因此，如果数据库允许您删除学生，那么您将拥有一个不连贯的数据库：考虑不存在的学生的出勤率。

因此，您必须在删除学生之前删除考勤。

请注意，实体之间存在的级联是无关紧要的，因为插入，更新和删除查询完全忽略它们。

JPA参照完整性约束违反oneToMany和批量操作查询

1 个答案: