给定一个名为 rating 的表在 MySQL 数据库中。
+-------------+---------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------------+---------------------+------+-----+---------+----------------+
| rating_id | bigint(20) unsigned | NO | PRI | NULL | auto_increment |
| prod_id | bigint(20) unsigned | YES | MUL | NULL | |
| rating_num | int(10) unsigned | YES | | NULL | |
| ip_address | varchar(45) | YES | | NULL | |
| row_version | bigint(20) unsigned | NO | | 0 | |
+-------------+---------------------+------+-----+---------+----------------+
我需要从该表中的一组行中获取行号。在 Oracle 中，
row_number()窗口函数是救命稻草。SELECT row_num
FROM (SELECT row_number() over (PARTITION BY prod_id ORDER BY rating_id DESC)
AS prod_id, rating_id, row_num FROM rating)
WHERE rating_id=? AND prod_id = ?;
但是 JPA 和 MySQL 都不支持窗口函数。因此，可以使用以下不同的 SQL 语句(基于
prod_id 的自连接)。SELECT a.prod_id, a.rating_id, count(*) as row_number
FROM rating a
INNER JOIN rating b ON a.prod_id = b.prod_id AND a.rating_id <= b.rating_id
GROUP BY a.prod_id, a.rating_id
ORDER BY a.prod_id, a.rating_id DESC
该语句返回以下结果集。
+---------+-----------+------------+
| prod_id | rating_id | row_number |
+---------+-----------+------------+
| 7 | 16 | 1 |
| 7 | 3 | 2 |
+---------+-----------+------------+
| 8 | 8 | 1 |
| 8 | 1 | 2 |
+---------+-----------+------------+
| 9 | 15 | 1 |
| 9 | 14 | 2 |
| 9 | 5 | 3 |
+---------+-----------+------------+
| 10 | 11 | 1 |
| 10 | 10 | 2 |
| 10 | 9 | 3 |
| 10 | 7 | 4 |
| 10 | 6 | 5 |
| 10 | 2 | 6 |
+---------+-----------+------------+
| 16 | 13 | 1 |
| 16 | 12 | 2 |
| 16 | 4 | 3 |
+---------+-----------+------------+
可以根据
rating_id 从上述结果集中检索与特定产品组关联的行号。 (主键)在连接中使用附加条件。现在可以完整地完成查询，如下所示。SELECT a.prod_id, a.rating_id, count(*) as row_number
FROM rating a
INNER JOIN rating b ON a.prod_id = b.prod_id AND a.rating_id <= b.rating_id
AND a.rating_id=?
GROUP BY a.prod_id, a.rating_id
ORDER BY a.prod_id, a.rating_id DESC
很明显，现在可以从结果集的第三列 (
row_number) 中选择特定产品组的行号(始终只有一行)。JPA 中的最终查询仍然很麻烦。以下标准查询不足以生成上述 SQL 语句。
CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
CriteriaQuery<Tuple> criteriaQuery = criteriaBuilder.createTupleQuery();
Root<Rating> root = criteriaQuery.from(entityManager.getMetamodel().entity(Rating.class));
criteriaQuery.multiselect(root.get(Rating_.product).get(Product_.prodId), root.get(Rating_.ratingId), criteriaBuilder.count(root));
Join<Rating, Rating> join = root.join(Rating_.rating, JoinType.INNER).on(criteriaBuilder.equal(root, rating));
criteriaQuery.where(criteriaBuilder.lessThanOrEqualTo(root.get(Rating_.ratingId), join.get(Rating_.ratingId)));
criteriaQuery.groupBy(root.get(Rating_.product).get(Product_.prodId), root.get(Rating_.ratingId));
criteriaQuery.orderBy(criteriaBuilder.desc(root.get(Rating_.product).get(Product_.prodId)), criteriaBuilder.desc(root.get(Rating_.ratingId)));
List<Tuple> list = entityManager.createQuery(criteriaQuery).getResultList();
Long rowNumber = list == null || list.isEmpty() ? 0L : list.get(0).get(2, Long.class);
上述条件查询对应的JPQL:
SELECT a.product.prodId, a.ratingId, COUNT(a) AS row_number
FROM Rating a INNER JOIN a.rating b ON a.ratingId=:ratingId
WHERE a.ratingId <= b.ratingId
GROUP BY a.product.prodId, a.ratingId
ORDER BY a.product.prodId, a.ratingId DESC
以上两个查询都会生成以下 SQL 语句。
select
rating0_.`prod_id` as col_0_0_,
rating0_.`rating_id` as col_1_0_,
count(rating0_.`rating_id`) as col_2_0_
from
`jboss_projectdb`.`rating` rating0_
inner join
`jboss_projectdb`.`rating` rating1_
on rating0_.`prod_id`=rating1_.`rating_id`
and (
rating0_.`rating_id`=?
)
where
rating0_.`rating_id`<=rating1_.`rating_id`
group by
rating0_.`prod_id` ,
rating0_.`rating_id`
order by
rating0_.`prod_id` desc,
rating0_.`rating_id` desc
注意生成的语句中的连接条件。
on rating0_.`prod_id`=rating1_.`rating_id`
不过应该是
on rating0_.`prod_id`=rating1_.`prod_id`
所以，问题是如何自我加入
rating表基于 prod_id (这是一个外键)？Rating中的自连接关系实体定义如下。@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "prod_id", insertable = false, updatable = false)
private Rating rating;
@OneToMany(fetch = FetchType.LAZY, mappedBy = "rating")
private List<Rating> ratingList;
我对使用以下非常特定于 MySQL 的语句从特定行组中获取行号不感兴趣。
SELECT
row_num
FROM
(SELECT @row_num := @row_num + 1 AS row_num, tbl.rating_id
FROM
rating tbl, (SELECT @row_num := 0) t
WHERE
tbl.prod_id=?
ORDER BY
tbl.rating_id DESC) t
WHERE
rating_id = ?
更新:
如果关系改变如下，
@JoinColumn(name = "prod_id", referencedColumnName = "prod_id", insertable = false, updatable = false)
@ManyToOne(fetch = FetchType.LAZY)
private Rating rating;
@JoinColumn(name = "prod_id", referencedColumnName = "prod_id")
@OneToMany(fetch = FetchType.LAZY)
private List<Rating> ratingList;
Hibernate 抛出以下异常。
16:43:52,609 WARNING [javax.enterprise.resource.webcontainer.jsf.lifecycle] (default task-18) javax.persistence.PersistenceException: org.hibernate.HibernateException: More than one row with the given identifier was found: entity.Rating[ratingId=null], for class: entity.Rating: service.app.exception.impl.DatabaseException: javax.persistence.PersistenceException: org.hibernate.HibernateException: More than one row with the given identifier was found: entity.Rating[ratingId=null], for class: entity.Rating
at service.ejb.interceptors.ExceptionInterceptor.handle(ExceptionInterceptor.java:32)
at sun.reflect.GeneratedMethodAccessor398.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.jboss.as.ee.component.ManagedReferenceLifecycleMethodInterceptor.processInvocation(ManagedReferenceLifecycleMethodInterceptor.java:89)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
at org.jboss.as.ejb3.component.invocationmetrics.ExecutionTimeInterceptor.processInvocation(ExecutionTimeInterceptor.java:43)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
at org.jboss.as.jpa.interceptor.SBInvocationInterceptor.processInvocation(SBInvocationInterceptor.java:47)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
at org.jboss.invocation.InterceptorContext$Invocation.proceed(InterceptorContext.java:437)
at org.jboss.weld.ejb.AbstractEJBRequestScopeActivationInterceptor.aroundInvoke(AbstractEJBRequestScopeActivationInterceptor.java:64)
at org.jboss.as.weld.ejb.EjbRequestScopeActivationInterceptor.processInvocation(EjbRequestScopeActivationInterceptor.java:83)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
at org.jboss.as.ee.concurrent.ConcurrentContextInterceptor.processInvocation(ConcurrentContextInterceptor.java:45)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
at org.jboss.invocation.InitialInterceptor.processInvocation(InitialInterceptor.java:21)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
at org.jboss.invocation.ChainedInterceptor.processInvocation(ChainedInterceptor.java:61)
at org.jboss.as.ee.component.interceptors.ComponentDispatcherInterceptor.processInvocation(ComponentDispatcherInterceptor.java:52)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
at org.jboss.as.ejb3.component.pool.PooledInstanceInterceptor.processInvocation(PooledInstanceInterceptor.java:51)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
at org.jboss.as.ejb3.tx.CMTTxInterceptor.invokeInOurTx(CMTTxInterceptor.java:275)
at org.jboss.as.ejb3.tx.CMTTxInterceptor.required(CMTTxInterceptor.java:327)
at org.jboss.as.ejb3.tx.CMTTxInterceptor.processInvocation(CMTTxInterceptor.java:239)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
at org.jboss.as.ejb3.component.interceptors.CurrentInvocationContextInterceptor.processInvocation(CurrentInvocationContextInterceptor.java:41)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
at org.jboss.as.ejb3.component.invocationmetrics.WaitTimeInterceptor.processInvocation(WaitTimeInterceptor.java:43)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
at org.jboss.as.ejb3.security.AuthorizationInterceptor.processInvocation(AuthorizationInterceptor.java:138)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
at org.jboss.as.ejb3.security.SecurityContextInterceptor.processInvocation(SecurityContextInterceptor.java:100)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
at org.jboss.as.ejb3.component.interceptors.ShutDownInterceptorFactory$1.processInvocation(ShutDownInterceptorFactory.java:64)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
at org.jboss.as.ejb3.component.interceptors.LoggingInterceptor.processInvocation(LoggingInterceptor.java:66)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
at org.jboss.as.ee.component.NamespaceContextInterceptor.processInvocation(NamespaceContextInterceptor.java:50)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
at org.jboss.as.ejb3.component.interceptors.AdditionalSetupInterceptor.processInvocation(AdditionalSetupInterceptor.java:54)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
at org.jboss.invocation.ContextClassLoaderInterceptor.processInvocation(ContextClassLoaderInterceptor.java:64)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
at org.jboss.invocation.InterceptorContext.run(InterceptorContext.java:356)
at org.wildfly.security.manager.WildFlySecurityManager.doChecked(WildFlySecurityManager.java:636)
at org.jboss.invocation.AccessCheckingInterceptor.processInvocation(AccessCheckingInterceptor.java:61)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
at org.jboss.invocation.InterceptorContext.run(InterceptorContext.java:356)
at org.jboss.invocation.PrivilegedWithCombinerInterceptor.processInvocation(PrivilegedWithCombinerInterceptor.java:80)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
at org.jboss.invocation.ChainedInterceptor.processInvocation(ChainedInterceptor.java:61)
at org.jboss.as.ee.component.ViewService$View.invoke(ViewService.java:195)
at org.jboss.as.ee.component.ViewDescription$1.processInvocation(ViewDescription.java:185)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
at org.jboss.invocation.ChainedInterceptor.processInvocation(ChainedInterceptor.java:61)
at org.jboss.as.ee.component.ProxyInvocationHandler.invoke(ProxyInvocationHandler.java:73)
at shareable.bean.ShareableService$$$view330.findRatingById(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.jboss.weld.util.reflection.Reflections.invokeAndUnwrap(Reflections.java:436)
at org.jboss.weld.bean.proxy.EnterpriseBeanProxyMethodHandler.invoke(EnterpriseBeanProxyMethodHandler.java:127)
at org.jboss.weld.bean.proxy.EnterpriseTargetBeanInstance.invoke(EnterpriseTargetBeanInstance.java:56)
at org.jboss.weld.bean.proxy.InjectionPointPropagatingEnterpriseTargetBeanInstance.invoke(InjectionPointPropagatingEnterpriseTargetBeanInstance.java:67)
at org.jboss.weld.bean.proxy.ProxyMethodHandler.invoke(ProxyMethodHandler.java:100)
at shareable.bean.ShareableService$614900122$Proxy$_$$_Weld$EnterpriseProxy$.findRatingById(Unknown Source)
at converter.RatingConverter.getAsObject(RatingConverter.java:41)
at com.sun.faces.renderkit.html_basic.HtmlBasicInputRenderer.getConvertedValue(HtmlBasicInputRenderer.java:171)
at javax.faces.component.UIViewParameter.getConvertedValue(UIViewParameter.java:437)
at javax.faces.component.UIInput.validate(UIInput.java:975)
at javax.faces.component.UIInput.executeValidate(UIInput.java:1248)
at javax.faces.component.UIInput.processValidators(UIInput.java:712)
at javax.faces.component.UIViewParameter.processValidators(UIViewParameter.java:278)
at org.omnifaces.component.input.ViewParam.processValidators(ViewParam.java:120)
at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1261)
at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1261)
at javax.faces.component.UIViewRoot.processValidators(UIViewRoot.java:1195)
at com.sun.faces.lifecycle.ProcessValidationsPhase.execute(ProcessValidationsPhase.java:76)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:198)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:658)
at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:85)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:129)
at org.primefaces.webapp.filter.FileUploadFilter.doFilter(FileUploadFilter.java:78)
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:60)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
at io.undertow.websockets.jsr.JsrWebSocketFilter.doFilter(JsrWebSocketFilter.java:129)
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:60)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
at org.omnifaces.facesviews.FacesViewsForwardingFilter.filterExtensionLess(FacesViewsForwardingFilter.java:128)
at org.omnifaces.facesviews.FacesViewsForwardingFilter.doFilter(FacesViewsForwardingFilter.java:89)
at org.omnifaces.filter.HttpFilter.doFilter(HttpFilter.java:108)
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:60)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
at filter.NoCacheFilter.doFilter(NoCacheFilter.java:33)
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:60)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
at org.omnifaces.filter.CharacterEncodingFilter.doFilter(CharacterEncodingFilter.java:122)
at org.omnifaces.filter.HttpFilter.doFilter(HttpFilter.java:108)
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:60)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
at io.undertow.servlet.handlers.FilterHandler.handleRequest(FilterHandler.java:84)
at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:62)
at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)
at org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest(SecurityContextAssociationHandler.java:78)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:131)
at io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:57)
at io.undertow.server.handlers.DisableCacheHandler.handleRequest(DisableCacheHandler.java:33)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.security.handlers.AuthenticationConstraintHandler.handleRequest(AuthenticationConstraintHandler.java:51)
at io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:46)
at io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:64)
at io.undertow.servlet.handlers.security.ServletSecurityConstraintHandler.handleRequest(ServletSecurityConstraintHandler.java:56)
at io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:60)
at io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:77)
at io.undertow.security.handlers.NotificationReceiverHandler.handleRequest(NotificationReceiverHandler.java:50)
at io.undertow.security.handlers.AbstractSecurityContextAssociationHandler.handleRequest(AbstractSecurityContextAssociationHandler.java:43)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at org.wildfly.extension.undertow.security.jacc.JACCContextIdHandler.handleRequest(JACCContextIdHandler.java:61)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:284)
at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:263)
at io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:81)
at io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:174)
at io.undertow.server.Connectors.executeRootHandler(Connectors.java:202)
at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:793)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: javax.persistence.PersistenceException: org.hibernate.HibernateException: More than one row with the given identifier was found: entity.Rating[ratingId=null], for class: entity.Rating
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1692)
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1602)
at org.hibernate.jpa.internal.QueryImpl.getResultList(QueryImpl.java:492)
at org.hibernate.jpa.criteria.compile.CriteriaQueryTypeQueryAdapter.getResultList(CriteriaQueryTypeQueryAdapter.java:50)
at shareable.bean.ShareableBean.findRatingById(ShareableBean.java:472)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.jboss.as.ee.component.ManagedReferenceMethodInterceptor.processInvocation(ManagedReferenceMethodInterceptor.java:52)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
at org.jboss.invocation.InterceptorContext$Invocation.proceed(InterceptorContext.java:437)
at org.jboss.as.weld.ejb.Jsr299BindingsInterceptor.doMethodInterception(Jsr299BindingsInterceptor.java:82)
at org.jboss.as.weld.ejb.Jsr299BindingsInterceptor.processInvocation(Jsr299BindingsInterceptor.java:93)
at org.jboss.as.ee.component.interceptors.UserInterceptorFactory$1.processInvocation(UserInterceptorFactory.java:63)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:340)
at org.jboss.invocation.InterceptorContext$Invocation.proceed(InterceptorContext.java:437)
at service.ejb.interceptors.ExceptionInterceptor.handle(ExceptionInterceptor.java:22)
... 133 more
Caused by: org.hibernate.HibernateException: More than one row with the given identifier was found: entity.Rating[ratingId=null], for class: entity.Rating
at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:86)
at org.hibernate.loader.entity.EntityLoader.loadByUniqueKey(EntityLoader.java:143)
at org.hibernate.persister.entity.AbstractEntityPersister.loadByUniqueKey(AbstractEntityPersister.java:2146)
at org.hibernate.type.EntityType.loadByUniqueKey(EntityType.java:685)
at org.hibernate.type.EntityType.resolve(EntityType.java:427)
at org.hibernate.engine.internal.TwoPhaseLoad.doInitializeEntity(TwoPhaseLoad.java:151)
at org.hibernate.engine.internal.TwoPhaseLoad.initializeEntity(TwoPhaseLoad.java:125)
at org.hibernate.loader.Loader.initializeEntitiesAndCollections(Loader.java:1132)
at org.hibernate.loader.Loader.processResultSet(Loader.java:992)
at org.hibernate.loader.Loader.doQuery(Loader.java:930)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:336)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:306)
at org.hibernate.loader.Loader.loadEntity(Loader.java:2197)
at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:60)
at org.hibernate.loader.entity.EntityLoader.loadByUniqueKey(EntityLoader.java:143)
at org.hibernate.persister.entity.AbstractEntityPersister.loadByUniqueKey(AbstractEntityPersister.java:2146)
at org.hibernate.type.EntityType.loadByUniqueKey(EntityType.java:685)
at org.hibernate.type.EntityType.resolve(EntityType.java:427)
at org.hibernate.engine.internal.TwoPhaseLoad.doInitializeEntity(TwoPhaseLoad.java:151)
at org.hibernate.engine.internal.TwoPhaseLoad.initializeEntity(TwoPhaseLoad.java:125)
at org.hibernate.loader.Loader.initializeEntitiesAndCollections(Loader.java:1132)
at org.hibernate.loader.Loader.processResultSet(Loader.java:992)
at org.hibernate.loader.Loader.doQuery(Loader.java:930)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:336)
at org.hibernate.loader.Loader.doList(Loader.java:2610)
at org.hibernate.loader.Loader.doList(Loader.java:2593)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2422)
at org.hibernate.loader.Loader.list(Loader.java:2417)
at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:501)
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:371)
at org.hibernate.engine.query.spi.HQLQueryPlan.performList(HQLQueryPlan.java:216)
at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1339)
at org.hibernate.internal.QueryImpl.list(QueryImpl.java:87)
at org.hibernate.jpa.internal.QueryImpl.list(QueryImpl.java:606)
at org.hibernate.jpa.internal.QueryImpl.getResultList(QueryImpl.java:483)
... 148 more
criteriaQuery.multiselect(...).distinct(true);没有帮助。所以，我认为可能不存在解决问题的方法。
最佳答案
Hibernate 完全按照您的映射告诉它做什么。构造 FROM Rating a INNER JOIN a.rating b表示将一个评级的主键与另一个评级的外键(引用该 PK)连接起来。
要通过映射实现您想要的效果，您必须显式构造连接条件，因此 from和 where您的 JPQL 子句可能如下所示:
SELECT ...
FROM Rating a, Rating b
WHERE a.rating.id = b.rating.id
AND a.ratingId = :ratingId
AND a.ratingId <= b.ratingId
GROUP BY ...
ORDER BY ...
rating.id翻译成 prod_id柱子。
关于hibernate - 使用 JPA 中的自联接从特定行组中检索行号，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/35961996/