JPA中具有ON条件的外部联接答案

【问题标题】：Outer joins with ON conditions in JPAJPA中具有ON条件的外部联接
【发布时间】：2013-07-24 12:32:50
【问题描述】：

我需要以下 SQL 查询的条件查询。

SELECT w.weight_id, w.weight, zc.charge
FROM weight w
LEFT OUTER JOIN zone_charge zc ON w.weight_id=zc.weight_id
AND zc.zone_id=?             <-------
ORDER BY w.weight ASC

相应的 JPQL 查询是这样的，

SELECT w.weightId, w.weight, zc.charge 
FROM Weight w 
LEFT JOIN w.zoneChargeSet zc 
WITH zc.zone.zoneId=:id      <-------
ORDER BY w.weight

我无法使用标准复制相同的内容，尤其是 WITH zc.zone.zoneId=:id。

以下条件查询使用where 子句。

CriteriaBuilder criteriaBuilder=entityManager.getCriteriaBuilder();
CriteriaQuery<Tuple>criteriaQuery=criteriaBuilder.createTupleQuery();
Root<Weight> root = criteriaQuery.from(entityManager.getMetamodel().entity(Weight.class));
SetJoin<Weight, ZoneCharge> join = root.join(Weight_.zoneChargeSet, JoinType.LEFT);

ParameterExpression<Long>parameterExpression=criteriaBuilder.parameter(Long.class);
criteriaQuery.where(criteriaBuilder.equal(join.get(ZoneCharge_.zoneTable).get(ZoneTable_.zoneId), parameterExpression));
criteriaQuery.multiselect(root.get(Weight_.weightId), root.get(Weight_.weight), join.get(ZoneCharge_.charge));
criteriaQuery.orderBy(criteriaBuilder.asc(root.get(Weight_.weight)));
TypedQuery<Tuple> typedQuery = entityManager.createQuery(criteriaQuery).setParameter(parameterExpression, 1L);
List<Tuple> list = typedQuery.getResultList();

如何修改使其对应...LEFT OUTER JOIN zone_charge zc ON w.weight_id=zc.weight_id AND zc.zone_id=?

这会生成以下 SQL 查询。

SELECT weight0_.weight_id  AS col_0_0_, 
       weight0_.weight     AS col_1_0_, 
       zonecharge1_.charge AS col_2_0_ 
FROM   social_networking.weight weight0_ 
       LEFT OUTER JOIN social_networking.zone_charge zonecharge1_ 
                    ON weight0_.weight_id = zonecharge1_.weight_id 
WHERE  zonecharge1_.zone_id =? 
ORDER  BY weight0_.weight ASC

【问题讨论】：

标签： hibernate jpa eclipselink criteria jpa-2.1

【解决方案1】：

with 运算符是 JPQL 的特定于休眠的扩展。您不会在条件 API 中找到对它的支持。

【讨论】：

所以，我只能选择 JPQL 吗？
是的，实际上是 HQL，因为 with 不是 JPQL 关键字。
Hibernate 标准是否支持它？反过来，此查询将是动态的，并且通过字符串连接构建查询有点乏味。
docs.jboss.org/hibernate/core/3.6/javadocs/org/hibernate/…
@Tiny我想知道如果使用JPQL代替createQuery，过滤条件将如何处理？例如。如果我的 DAOImpl 方法接收到任何过滤条件，并且如果我想作为过滤条件的参数传递给 JPQL，我的查询应该是 like % 可能有性能问题不是吗？

【解决方案2】：

这可以与JPA 2.1 提供的标准API 一起使用新功能join ON clause 来完成。因此，问题中给出的条件查询可以重写如下。

CriteriaBuilder criteriaBuilder=entityManager.getCriteriaBuilder();
CriteriaQuery<Tuple>criteriaQuery=criteriaBuilder.createQuery(Tuple.class);
Root<Weight> root = criteriaQuery.from(entityManager.getMetamodel().entity(Weight.class));

ListJoin<Weight, ZoneCharge> join = root.join(Weight_.zoneChargeList, JoinType.LEFT);
criteriaQuery.multiselect(root.get(Weight_.weightId), root.get(Weight_.weight), join.get(ZoneCharge_.charge));

ParameterExpression<Long>parameterExpression=criteriaBuilder.parameter(Long.class);
join.on(criteriaBuilder.equal(join.get(ZoneCharge_.zoneTable).get(ZoneTable_.zoneId), parameterExpression));

criteriaQuery.orderBy(criteriaBuilder.asc(root.get(Weight_.weight)));
List<Tuple> list = entityManager.createQuery(criteriaQuery).setParameter(parameterExpression, 1L).getResultList();

它产生以下所需的 SQL 查询。

SELECT weight0_.weight_id  AS col_0_0_, 
       weight0_.weight     AS col_1_0_, 
       zonecharge1_.charge AS col_2_0_ 
FROM   social_networking.weight weight0_ 
       LEFT OUTER JOIN social_networking.zone_charge zonecharge1_ 
                    ON weight0_.weight_id = zonecharge1_.weight_id 
                       AND ( zonecharge1_.zone_id =? ) 
ORDER  BY weight0_.weight ASC

值得一提的是，此查询在 Hibernate (4.3.5 final) 上成功，但相同的查询在 EclipseLink (2.5.1) 上意外失败，并出现以下异常。

java.lang.IllegalArgumentException: No parameter with name : Parameter[name=null] was found within the query: ReportQuery(referenceClass=Weight ).
    at org.eclipse.persistence.internal.jpa.EJBQueryImpl.setParameter(EJBQueryImpl.java:548)
    at admin.beans.ZoneChargeBean.getZoneChargeList(ZoneChargeBean.java:83)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at org.glassfish.ejb.security.application.EJBSecurityManager.runMethod(EJBSecurityManager.java:1081)
    at org.glassfish.ejb.security.application.EJBSecurityManager.invoke(EJBSecurityManager.java:1153)
    at com.sun.ejb.containers.BaseContainer.invokeBeanMethod(BaseContainer.java:4695)
    at com.sun.ejb.EjbInvocation.invokeBeanMethod(EjbInvocation.java:630)
    at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:822)
    at com.sun.ejb.EjbInvocation.proceed(EjbInvocation.java:582)
    at org.jboss.weld.ejb.AbstractEJBRequestScopeActivationInterceptor.aroundInvoke(AbstractEJBRequestScopeActivationInterceptor.java:46)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at com.sun.ejb.containers.interceptors.AroundInvokeInterceptor.intercept(InterceptorManager.java:883)
    at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:822)
    at com.sun.ejb.EjbInvocation.proceed(EjbInvocation.java:582)
    at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.doCall(SystemInterceptorProxy.java:163)
    at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.aroundInvoke(SystemInterceptorProxy.java:140)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at com.sun.ejb.containers.interceptors.AroundInvokeInterceptor.intercept(InterceptorManager.java:883)
    at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:822)
    at com.sun.ejb.containers.interceptors.InterceptorManager.intercept(InterceptorManager.java:369)
    at com.sun.ejb.containers.BaseContainer.__intercept(BaseContainer.java:4667)
    at com.sun.ejb.containers.BaseContainer.intercept(BaseContainer.java:4655)
    at com.sun.ejb.containers.EJBLocalObjectInvocationHandler.invoke(EJBLocalObjectInvocationHandler.java:212)
    ... 72 more

ParamterExpression 必须被删除才能按如下方式工作。

CriteriaBuilder criteriaBuilder=entityManager.getCriteriaBuilder();
CriteriaQuery<Tuple>criteriaQuery=criteriaBuilder.createQuery(Tuple.class);
Root<Weight> root = criteriaQuery.from(entityManager.getMetamodel().entity(Weight.class));

ListJoin<Weight, ZoneCharge> join = root.join(Weight_.zoneChargeList, JoinType.LEFT);

criteriaQuery.multiselect(root.get(Weight_.weightId), root.get(Weight_.weight), join.get(ZoneCharge_.charge));
join.on(criteriaBuilder.equal(join.get(ZoneCharge_.zoneTable).get(ZoneTable_.zoneId), 1L));

criteriaQuery.orderBy(criteriaBuilder.asc(root.get(Weight_.weight)));
List<Tuple> list = entityManager.createQuery(criteriaQuery).getResultList();

这应该是 EclipseLink 2.5.1 中的一个疏忽。

【讨论】：