我如何摆脱“MySQLSyntaxErrorException”

Question

我目前正在使用 hibernate 构建一个基于 Web 的小工具。 我使用 Tomcat v7.0 服务器在 Eclipse 中测试运行该站点。 我的数据库在 Linux 上使用 MySQL 5.6 版。

现在，每次我运行该程序，在服务器上启动我的 index.xhtml 时，我都会收到一条令人发指的错误消息，如下所示：

ERROR: HHH000300: Could not complete schema validation
com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown table 'system_sequences' in information_schema
    at sun.reflect.GeneratedConstructorAccessor48.newInstance(Unknown Source)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:422)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:377)
    at com.mysql.jdbc.Util.getInstance(Util.java:360)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:978)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3887)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3823)
    at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2435)
    at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2582)
    at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2526)
    at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2484)
    at com.mysql.jdbc.StatementImpl.executeQuery(StatementImpl.java:1446)
    at org.hibernate.tool.hbm2ddl.DatabaseMetadata.initSequences(DatabaseMetadata.java:178)
    at org.hibernate.tool.hbm2ddl.DatabaseMetadata.<init>(DatabaseMetadata.java:92)
    at org.hibernate.tool.hbm2ddl.SchemaValidator.validate(SchemaValidator.java:168)
    at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:525)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1859)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1930)
    at com.ubs.tbt.database.KurseDAO.getModule(KurseDAO.java:139)
    at com.ubs.tbt.database.Klasse.module(Klasse.java:59)
    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 javax.el.BeanELResolver.invoke(BeanELResolver.java:165)
    at javax.el.CompositeELResolver.invoke(CompositeELResolver.java:84)
    at org.apache.el.parser.AstValue.getValue(AstValue.java:159)
    at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:184)
    at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:109)
    at com.sun.faces.facelets.component.UIRepeat.getValue(UIRepeat.java:274)
    at com.sun.faces.facelets.component.UIRepeat.getDataModel(UIRepeat.java:250)
    at com.sun.faces.facelets.component.UIRepeat.setIndex(UIRepeat.java:444)
    at com.sun.faces.facelets.component.UIRepeat.doVisitChildren(UIRepeat.java:679)
    at com.sun.faces.facelets.component.UIRepeat.visitTree(UIRepeat.java:637)
    at javax.faces.component.UIComponent.visitTree(UIComponent.java:1700)
    at javax.faces.component.UIForm.visitTree(UIForm.java:371)
    at javax.faces.component.UIComponent.visitTree(UIComponent.java:1700)
    at javax.faces.component.UIComponent.visitTree(UIComponent.java:1700)
    at org.primefaces.component.api.UITabPanel.visitTree(UITabPanel.java:920)
    at com.sun.faces.facelets.component.UIRepeat.visitTree(UIRepeat.java:643)
    at javax.faces.component.UIComponent.visitTree(UIComponent.java:1700)
    at javax.faces.component.UIComponent.visitTree(UIComponent.java:1700)
    at com.sun.faces.application.view.FaceletPartialStateManagementStrategy.saveView(FaceletPartialStateManagementStrategy.java:472)
    at com.sun.faces.application.StateManagerImpl.saveView(StateManagerImpl.java:89)
    at javax.faces.application.StateManager.getViewState(StateManager.java:593)
    at com.sun.faces.context.PartialViewContextImpl.renderState(PartialViewContextImpl.java:454)
    at com.sun.faces.context.PartialViewContextImpl.processPartial(PartialViewContextImpl.java:322)
    at org.primefaces.context.PrimePartialViewContext.processPartial(PrimePartialViewContext.java:60)
    at javax.faces.component.UIViewRoot.encodeChildren(UIViewRoot.java:1004)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1856)
    at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:417)
    at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:131)
    at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:120)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:219)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:647)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:617)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:668)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1521)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1478)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)

我的 hibernate.cfg

<?xml version='1.0'?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>

        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://192.168.1.34:3306/BeurteilungsDB</property>
        <property name="connection.username">admin</property>
        <property name="connection.password">po2015</property>

        <!-- Zusaetzliche Hibernate-Properties -->
        <property name="hibernate.dialect">org.hibernate.dialect.HSQLDialect</property>
        <property name="hibernate.format_sql">true</property>
        <property name="hibernate.current_session_context_class">thread</property>

        <property name="hibernate.hbm2ddl.auto">validate</property>

        <!-- Definition der gemappten Klassen -->

    <!--    <mapping class="ch.fg.bibliothek.Verlag" />-->
        <mapping class="com.ubs.tbt.database.Eventbewertung" />
        <mapping class="com.ubs.tbt.database.Modulbewertung" />
        <mapping class="com.ubs.tbt.database.Teilnehmer" />
        <mapping class="com.ubs.tbt.database.Klasse" />
        <mapping class="com.ubs.tbt.database.Firma" />
        <mapping class="com.ubs.tbt.database.Kursleiter" />
        <mapping class="com.ubs.tbt.database.Module" />
        <mapping class="com.ubs.tbt.database.Kurse" />

    </session-factory>


</hibernate-configuration>

程序本身正常运行并按预期方式工作，但是当控制台中每隔一行打印此消息时，我很难验证控制台输出的其余部分。

值得一提的是，我在<property name="hibernate.hbm2ddl.auto">validate</property>添加关键字validate后开始收到此消息。

这个表应该在哪里，最重要的是，我如何摆脱这个消息？

Answer 1

首先你需要了解hibernate映射到ddl，hbm2ddl.auto设置。

从文档hibernate.hbm2ddl.auto ：

创建 SessionFactory 时自动验证或导出模式 DDL 到数据库。 使用 create-drop，当 SessionFactory 显式关闭时，数据库模式将被删除。 例如验证| 更新 | 创建 | 创建删除

validate:验证架构，不对数据库进行任何更改。

update:更新架构。

create:创建模式，销毁以前的数据。

create-drop:在会话结束时删除模式。

您的配置无法验证架构，因为它找不到information_schema 。 system_sequences 。 我想是因为你选择了方言。

尝试更换与org.hibernate.dialect.MySQLDialect的org.hibernate.dialect.HSQLDialect

查看 doc url 以选择正确的方言，并验证配置的其余部分。

MySQL 休眠方言：

MySQL               org.hibernate.dialect.MySQLDialect
MySQL with InnoDB   org.hibernate.dialect.MySQLInnoDBDialect
MySQL with MyISAM   org.hibernate.dialect.MySQLMyISAMDialect

information_schema是 MySQL 自己的信息数据库。 它包含有关在其数据库服务器中维护的所有其他（您自己的）数据库的所有信息。

Answer 2

更改org.hibernate.dialect.HSQLDialect到org.hibernate.dialect.MySQLDialect 。 在你的 application.properties 你应该有spring.jpa.database-platform=org.hibernate.dialect.MySQLDialect它与 MySQL Connector 8 一起工作。