java - Hibernate映射思维错误

Question

我有 2 个数据库表。首先有交易。每笔交易都有一个 ID。这个 ID 也可以在我的第二张表中找到。第二个表包含费用，但我的第一个表没有有关费用的信息。现在我必须通过 hibernate 映射获取与 1 笔交易相关的所有费用，但我不想在两个方向都有它。

贸易类别:

public class Trade {
    @Id
    @Column(name = "ID")
    private Long tradeTag;

    @ElementCollection
    @CollectionTable(name = "VIE_CHARGES", joinColumns = 
    @JoinColumn(name="TRADE"))
    private List<Charge> charges;
}

收费类别:

public class Charge implements Serializable{

    private static final long serialVersionUID = 1L;
    @Id
    private String chargeType;
    @Id
    @Column(name="TRADE")
    private Long tradeTag;
}

在收费类别中，我不想保留有关交易的任何信息，但在交易类别中保留该交易的所有费用的列表。我很高兴在这里得到解决方案，因为我真的不知道该怎么做。

查看收费:

create view VIE_CHARGES as 
select CHRG_TYPE AS CHARGETYPE
,TRAD_TAG AS TRADE
from TRADE_CHARGE

交易 View :

create VIEW VIE_TRADE AS 
select TRAD_TAG as ID
from TRADE 

错误是:

org.hibernate.exception.SQLGrammarException: could not extract ResultSet at org.hibernate.exception.internal.SQLStateConversionDelegate.convert(SQLStateConversionDelegate.java:106) at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:42) at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:111) at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:97) at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.extract(ResultSetReturnImpl.java:79) at org.hibernate.loader.Loader.getResultSet(Loader.java:2123) at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1911) at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1887) at org.hibernate.loader.Loader.doQuery(Loader.java:932) at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:349) at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:319) at org.hibernate.loader.Loader.loadCollection(Loader.java:2327) at org.hibernate.loader.collection.plan.LegacyBatchingCollectionInitializerBuilder$LegacyBatchingCollectionInitializer.initialize(LegacyBatchingCollectionInitializerBuilder.java:88) at org.hibernate.persister.collection.AbstractCollectionPersister.initialize(AbstractCollectionPersister.java:688) at org.hibernate.event.internal.DefaultInitializeCollectionEventListener.onInitializeCollection(DefaultInitializeCollectionEventListener.java:75) at org.hibernate.internal.SessionImpl.initializeCollection(SessionImpl.java:2150) at org.hibernate.collection.internal.AbstractPersistentCollection$4.doWork(AbstractPersistentCollection.java:567) at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:249) at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:563) at org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:132) at org.hibernate.collection.internal.AbstractPersistentCollection$1.doWork(AbstractPersistentCollection.java:161) at org.hibernate.collection.internal.AbstractPersistentCollection$1.doWork(AbstractPersistentCollection.java:146) at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:249) at org.hibernate.collection.internal.AbstractPersistentCollection.readSize(AbstractPersistentCollection.java:145) at org.hibernate.collection.internal.PersistentBag.size(PersistentBag.java:261) at com.mainfirst.emma.archive.trade.rims.TestDataBaseconnection.testTradeDao(TestDataBaseconnection.java:28) 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:50) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75) at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86) at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84) at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:252) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61) at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70) at org.junit.runners.ParentRunner.run(ParentRunner.java:363) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191) at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:678) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192) Caused by: com.microsoft.sqlserver.jdbc.SQLServerException: Invalid column name 'charges_TRADE'. at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDatabaseError(SQLServerException.java:216) at com.microsoft.sqlserver.jdbc.SQLServerStatement.getNextResult(SQLServerStatement.java:1515) at com.microsoft.sqlserver.jdbc.SQLServerPreparedStatement.doExecutePreparedStatement(SQLServerPreparedStatement.java:404) at com.microsoft.sqlserver.jdbc.SQLServerPreparedStatement$PrepStmtExecCmd.doExecute(SQLServerPreparedStatement.java:350) at com.microsoft.sqlserver.jdbc.TDSCommand.execute(IOBuffer.java:5696) at com.microsoft.sqlserver.jdbc.SQLServerConnection.executeCommand(SQLServerConnection.java:1715) at com.microsoft.sqlserver.jdbc.SQLServerStatement.executeCommand(SQLServerStatement.java:180) at com.microsoft.sqlserver.jdbc.SQLServerStatement.executeStatement(SQLServerStatement.java:155) at com.microsoft.sqlserver.jdbc.SQLServerPreparedStatement.executeQuery(SQLServerPreparedStatement.java:285) at org.apache.commons.dbcp2.DelegatingPreparedStatement.executeQuery(DelegatingPreparedStatement.java:83) at org.apache.commons.dbcp2.DelegatingPreparedStatement.executeQuery(DelegatingPreparedStatement.java:83) at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.extract(ResultSetReturnImpl.java:70) ... 50 more

Answer 1

如果费用对象不需要自己的生命周期(没有自己的标识符，不被多个交易引用，不应该单独存在，应该与它的交易一起删除)，您可以将其映射为@ElementCollection 值类型 (@Embeddable)。

映射表和id列名可以通过@CollectionTable和@JoinColumn注解设置。它的默认值是“trade_charges”和“trade_id”。

@OrderColumn 注解只是一点点性能提升，只有当你面对集合的大量更改时才需要它。它向 trade_charges 表添加一个索引列，以识别更新/删除语句中的行。

例如贸易:

@Entity
public class Trade {

    @Id
    @Column(name = "ID")
    private Long tradeTag;

    @ElementCollection
    @CollectionTable(name = "charges", joinColumns = @JoinColumn(name="ID"))
    @OrderColumn
    private List<Charge> charges;

}

费用:

@Embeddable
public class Charge {

    private String chargeType;

}