我正在使用带有spring的hibernate。但是，在添加.distinct(true)之类的criteria.select(cb.construct(Customer.class, root.get("Name"))).distinct(true);时。然后我收到以下异常：
Exception in thread "AWT-EventQueue-0" javax.persistence.PersistenceException: org.hibernate.exception.SQLGrammarException: could not prepare statement
at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1387)
at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1310)
at org.hibernate.ejb.QueryImpl.getResultList(QueryImpl.java:273)
at org.hibernate.ejb.criteria.CriteriaQueryCompiler$3.getResultList(CriteriaQueryCompiler.java:254)
at com.limitCalculator.dao.FilterDaoImpl.getFilter(FilterDaoImpl.java:83)
at com.limitCalculator.dao.FilterDaoImpl$$FastClassByCGLIB$$a62bf500.invoke(<generated>)
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:698)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:96)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:260)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:94)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:631)
at com.limitCalculator.dao.FilterDaoImpl$$EnhancerByCGLIB$$6ca0bd06.getFilter(<generated>)
at com.limitCalculator.service.FilterServiceImpl.getFilter(FilterServiceImpl.java:37)
at com.limitCalculator.gui.timerSelection.MainTabPanel.placeSelectionWithButtons(MainTabPanel.java:137)
at com.limitCalculator.gui.timerSelection.MainTabPanel.createLayout(MainTabPanel.java:111)
at com.limitCalculator.gui.timerSelection.MainWindow.createTabBar(MainWindow.java:132)
at com.limitCalculator.gui.timerSelection.MainWindow.makeLayout(MainWindow.java:182)
at com.limitCalculator.gui.timerSelection.MainWindow.access$1(MainWindow.java:172)
at com.limitCalculator.gui.timerSelection.MainWindow$4.run(MainWindow.java:197)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$400(Unknown Source)
at java.awt.EventQueue$2.run(Unknown Source)
at java.awt.EventQueue$2.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
Caused by: org.hibernate.exception.SQLGrammarException: could not prepare statement
at org.hibernate.exception.internal.SQLExceptionTypeDelegate.convert(SQLExceptionTypeDelegate.java:82)
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:125)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$StatementPreparationTemplate.prepareStatement(StatementPreparerImpl.java:188)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.prepareQueryStatement(StatementPreparerImpl.java:159)
at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1854)
at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1831)
at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1811)
at org.hibernate.loader.Loader.doQuery(Loader.java:899)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:341)
at org.hibernate.loader.Loader.doList(Loader.java:2516)
at org.hibernate.loader.Loader.doList(Loader.java:2502)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2332)
at org.hibernate.loader.Loader.list(Loader.java:2327)
at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:490)
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:355)
at org.hibernate.engine.query.spi.HQLQueryPlan.performList(HQLQueryPlan.java:195)
at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1268)
at org.hibernate.internal.QueryImpl.list(QueryImpl.java:101)
at org.hibernate.ejb.QueryImpl.getResultList(QueryImpl.java:264)
... 33 more
Caused by: java.sql.SQLSyntaxErrorException: invalid ORDER BY expression
at org.hsqldb.jdbc.JDBCUtil.sqlException(Unknown Source)
at org.hsqldb.jdbc.JDBCUtil.sqlException(Unknown Source)
at org.hsqldb.jdbc.JDBCPreparedStatement.<init>(Unknown Source)
at org.hsqldb.jdbc.JDBCConnection.prepareStatement(Unknown Source)
at org.apache.commons.dbcp.DelegatingConnection.prepareStatement(DelegatingConnection.java:281)
at org.apache.commons.dbcp.PoolingDataSource$PoolGuardConnectionWrapper.prepareStatement(PoolingDataSource.java:313)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$5.doPrepare(StatementPreparerImpl.java:161)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$StatementPreparationTemplate.prepareStatement(StatementPreparerImpl.java:182)
... 49 more
我的hibernate查询看起来像这样：
Hibernate：
select distinct customer0_.Name as col_0_0_
from Customer customer0_
where (upper(customer0_.Name) like ?) and (upper(customer0_.City) like ?) and
(upper(customer0_.Country) like ?)
order by customer0_.customerNr asc
这就是我正在使用的代码：
@Transactional
@SuppressWarnings("all")
public List<Customer> getFilter(String city, String country) {
CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<Customer> criteria = cb.createQuery(Customer.class);
//which table we want to fetch
final Root root = criteria.from(Customer.class);
List criteriaList = createWhereCritera(city, country, cb, root);
//create statement
criteria.select(cb.construct(Customer.class, root.get("Name"))).distinct(true);
// Pass the criteria list to the where method of criteria query
criteria.where(cb.and((Predicate[]) criteriaList.toArray(new Predicate[0])));
// Order by clause
criteria.orderBy(cb.asc(root.get("customerNr")));
return em.createQuery(criteria).getResultList();
}
public List createWhereCritera(String city, String country, CriteriaBuilder cb,
final Root root) {
// This list will contain all Predicates (where clauses)
List criteriaList = new ArrayList();
// City:
Predicate predicateCity = cb.like(cb.upper(root.get("City")),city);
criteriaList.add(predicateCity);
// Country:
Predicate predicateCountry = cb.like(cb.upper(root.get("Country")),country);
criteriaList.add(predicateCountry);
return criteriaList;
}
任何建议，为什么会出现此问题以及如何获取所有不同的值？
感谢您的回答！
答案 0 :(得分：1)
您的查询错误。
无论Order By has to be a part of Select clause中有什么。
当存在ORDER BY子句时，它是最后执行的子句。首先，FROM子句生成要检查的对象，WHERE子句选择要收集哪些对象作为结果。然后SELECT子句通过计算结果表达式来构建结果。最后，通过评估ORDER BY表达式来排序结果。
在ORDER BY子句中只允许直接从SELECT子句中的表达式派生的表达式。以下查询无效，因为ORDER BY表达式不是结果的一部分：
SELECT c.name
FROM Country c
WHERE c.population > 1000000
ORDER BY c.population
另一方面，以下查询有效，因为在给定国家c的情况下，可以从c评估c.population表达式：
SELECT c
FROM Country c
WHERE c.population > 1000000
ORDER BY c.population
所以请将您的查询更改为以下内容。
select distinct (customer0_.Name as col_0_0_), customer0_.customerNr from Customer customer0_ where (upper(customer0_.Name) like ?) and (upper(customer0_.City) like ?) and (upper(customer0_.Country) like ?) order by customer0_.customerNr asc
答案 1 :(得分：0)
对于条件查询，您可以根据根表的主键列通过group by进行重复数据删除：
criteria.groupBy(root.get("id")); // Assuming that Customer.id is primary key column