这是一个优惠券系统。实体是公司，客户，优惠券。公司生成优惠券。每个公司都有自己的优惠券集合，有很多（优惠券）_To_ONE（公司）关系。任何客户都可以购买任何优惠券。这反映了许多（客户）_To_MANY（优惠券）关系。
任何优惠券都可以删除。创建它的公司决定删除它，或者它的EndDate被传递并被每日线程自动删除。应该发生什么：一旦被删除 - 创建它的公司 - 不再拥有它，任何购买它的客户 - 不再持有它，它的记录应该完全消失。
在实践中：我可以手动删除优惠券，如果没有客户持有，可以自动删除优惠券。但是，如果客户持有优惠券，并且我尝试删除此优惠券，则会收到错误消息：
org.apache.derby.client.am.SqlException: DELETE on table 'COUPON' caused a violation of foreign key constraint 'FKPPNDQDPYDMSUMC9YQSLM5HSS4' for key (21). The statement has been rolled back.
at org.apache.derby.client.am.ClientStatement.completeExecute(Unknown Source) ~[derbyclient-10.11.1.1.jar:na]
at org.apache.derby.client.net.NetStatementReply.parseEXCSQLSTTreply(Unknown Source) ~[derbyclient-10.11.1.1.jar:na]
at org.apache.derby.client.net.NetStatementReply.readExecute(Unknown Source) ~[derbyclient-10.11.1.1.jar:na]
at org.apache.derby.client.net.StatementReply.readExecute(Unknown Source) ~[derbyclient-10.11.1.1.jar:na]
at org.apache.derby.client.net.NetPreparedStatement.readExecute_(Unknown Source) ~[derbyclient-10.11.1.1.jar:na]
at org.apache.derby.client.am.ClientPreparedStatement.readExecute(Unknown Source) ~[derbyclient-10.11.1.1.jar:na]
at org.apache.derby.client.am.ClientPreparedStatement.flowExecute(Unknown Source) ~[derbyclient-10.11.1.1.jar:na]
at org.apache.derby.client.am.ClientPreparedStatement.executeUpdateX(Unknown Source) ~[derbyclient-10.11.1.1.jar:na]
at org.apache.derby.client.am.ClientPreparedStatement.executeUpdate(Unknown Source) ~[derbyclient-10.11.1.1.jar:na]
at com.zaxxer.hikari.pool.ProxyPreparedStatement.executeUpdate(ProxyPreparedStatement.java:61) ~[HikariCP-2.7.9.jar:na]
at com.zaxxer.hikari.pool.HikariProxyPreparedStatement.executeUpdate(HikariProxyPreparedStatement.java) ~[HikariCP-2.7.9.jar:na]
at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:175) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
at org.hibernate.engine.jdbc.batch.internal.NonBatchingBatch.addToBatch(NonBatchingBatch.java:45) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
at org.hibernate.persister.entity.AbstractEntityPersister.delete(AbstractEntityPersister.java:3339) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
at org.hibernate.persister.entity.AbstractEntityPersister.delete(AbstractEntityPersister.java:3596) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
at org.hibernate.action.internal.EntityDeleteAction.execute(EntityDeleteAction.java:99) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:600) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:474) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
at org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:337) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:39) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
at org.hibernate.internal.SessionImpl.doFlush(SessionImpl.java:1437) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:494) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
at org.hibernate.internal.SessionImpl.flushBeforeTransactionCompletion(SessionImpl.java:3245) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
at org.hibernate.internal.SessionImpl.beforeTransactionCompletion(SessionImpl.java:2451) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
at org.hibernate.engine.jdbc.internal.JdbcCoordinatorImpl.beforeTransactionCompletion(JdbcCoordinatorImpl.java:473) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.beforeCompletionCallback(JdbcResourceLocalTransactionCoordinatorImpl.java:156) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.access$100(JdbcResourceLocalTransactionCoordinatorImpl.java:38) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl$TransactionDriverControlImpl.commit(JdbcResourceLocalTransactionCoordinatorImpl.java:231) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
at org.hibernate.engine.transaction.internal.TransactionImpl.commit(TransactionImpl.java:68) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:536) ~[spring-orm-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:746) ~[spring-tx-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:714) ~[spring-tx-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.transaction.interceptor.TransactionAspectSupport.commitTransactionAfterReturning(TransactionAspectSupport.java:532) ~[spring-tx-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:304) ~[spring-tx-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:98) ~[spring-tx-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185) ~[spring-aop-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139) ~[spring-tx-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185) ~[spring-aop-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:135) ~[spring-data-jpa-2.0.9.RELEASE.jar:2.0.9.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185) ~[spring-aop-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92) ~[spring-aop-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185) ~[spring-aop-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.data.repository.core.support.SurroundingTransactionDetectorMethodInterceptor.invoke(SurroundingTransactionDetectorMethodInterceptor.java:61) ~[spring-data-commons-2.0.9.RELEASE.jar:2.0.9.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185) ~[spring-aop-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212) ~[spring-aop-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at com.sun.proxy.$Proxy98.delete(Unknown Source) ~[na:na]
at cs5.services.CompanyFacade.removeCoupon(CompanyFacade.java:103) ~[classes/:na]
at cs5.controllers.CompanyController.removeCoupon(CompanyController.java:55) ~[classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_171]
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_171]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_171]
at java.lang.reflect.Method.invoke(Unknown Source) ~[na:1.8.0_171]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:209) ~[spring-web-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136) ~[spring-web-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102) ~[spring-webmvc-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:877) ~[spring-webmvc-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:783) ~[spring-webmvc-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:991) ~[spring-webmvc-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925) ~[spring-webmvc-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:974) ~[spring-webmvc-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:877) ~[spring-webmvc-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:661) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851) ~[spring-webmvc-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-embed-websocket-8.5.32.jar:8.5.32]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
at cs5.filters.SessionFilter.doFilter(SessionFilter.java:43) ~[classes/:na]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:109) ~[spring-web-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93) ~[spring-web-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200) ~[spring-web-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.8.RELEASE.jar:5.0.8.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) ~[tomcat-embed-core-8.5.32.jar:8.5.32]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-8.5.32.jar:8.5.32]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:493) [tomcat-embed-core-8.5.32.jar:8.5.32]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [tomcat-embed-core-8.5.32.jar:8.5.32]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81) [tomcat-embed-core-8.5.32.jar:8.5.32]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [tomcat-embed-core-8.5.32.jar:8.5.32]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) [tomcat-embed-core-8.5.32.jar:8.5.32]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:800) [tomcat-embed-core-8.5.32.jar:8.5.32]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-8.5.32.jar:8.5.32]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:800) [tomcat-embed-core-8.5.32.jar:8.5.32]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1471) [tomcat-embed-core-8.5.32.jar:8.5.32]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-8.5.32.jar:8.5.32]
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [na:1.8.0_171]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [na:1.8.0_171]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.5.32.jar:8.5.32]
at java.lang.Thread.run(Unknown Source) [na:1.8.0_171]
CompanyFacade（保存公司的所有业务逻辑，验证信息并调用JpaRepository方法）removeCoupon（）：
public void removeCoupon(Coupon coupon) throws ConnectionPoolException, DAOException, CouponDontExistException {
if (couponDao.getOne(coupon.getId()) != null) {
couponDao.delete(coupon);
} else {
throw new CouponDontExistException(
"Failed to remove Coupon. coupon with id " + coupon.getId() + " cannot be found;");
}
}
优惠券（定义与COMPANY的关系）
@Entity
public class Coupon {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private long id;
private String title;
@Column(name = "startDate")
private Date startDate;
@Column(name = "endDate")
private Date endDate;
private int amount;
private CouponType type;
private String message;
private double price;
private String image;
@ManyToOne(fetch = FetchType.LAZY, optional = false)
@JoinColumn(name = "company_id", nullable = false)
@OnDelete(action = OnDeleteAction.CASCADE)
@JsonIgnore
private Company company;
公司
@Entity
public class Company {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private long id;
@Column(unique = true)
private String compName;
private String password;
private String email;
客户（定义与COUPON的关系）
@Entity
public class Customer {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private long id;
@Column(unique = true)
private String custName;
private String password;
@ManyToMany(fetch = FetchType.LAZY)
@JoinTable(name = "CUSTOMER_COUPON", joinColumns = @JoinColumn(name = "customerId"), inverseJoinColumns = @JoinColumn(name = "couponId"))
private Set<Coupon> coupons;
我错过了什么？其他一切都很完美。您的建议将不胜感激。
从我的角度来看，你有一个
@OnDelete（action = OnDeleteAction.CASCADE）
在您的优惠券定义中，在那里不需要。但它在Customers ManyToMany关系中是必需的。那是因为当您删除优惠券时，该关系将转移到公司，因此此处不需要删除级联。
当客户持有优惠券的多对多参考时，您需要级联删除，或者您必须删除m-2-m关系才能删除优惠券。
解决：我想，因为在Customer实体上定义了Many To Many关系，并且现成的hibernate JPA接口在这里不会有用，我将不得不编写自己的自定义查询：
String query = "DELETE FROM customer_coupon WHERE coupon_id = ";
query += coupon.getId();
这被证明是困难的，因为JPArepository不会接受这种原生SQL，我无法弄清楚JPQL语法，或者它完全是不可能的：继续得到一个例外，即customer_coupon表没有映射（尽管它确实存在）。
出于这个原因，我必须找到一种方法来使用spring的EntityManager并直接在DB上执行自定义查询，每个JPA操作都可能需要它们。为此，我用显式方法编写了一个实用程序存储库类。这样做的伎俩：
@Service
public class UtilRespository {
@PersistenceContext
private EntityManager em;
@Transactional
public int removeCouponOwnership(Coupon coupon) {
String query = "DELETE FROM customer_coupon WHERE coupon_id = ";
query += coupon.getId();
Query q = em.createNativeQuery(query);
int removed = q.executeUpdate();
em.close();
System.out.println("Successfully removed Coupon " + coupon.getId() + " from " + removed + " customers;");
return removed;
}
}