Question

我正在尝试使用hibernate在数据库中保存对象。当我第一次使用新的表名运行代码时，它会抛出错误，但是当我第二次运行它时它完全正常 -

    INFO: HHH10001501: Connection obtained from JdbcConnectionAccess [org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator$ConnectionProviderJdbcConnectionAccess@61ce23ac] for (non-JTA) DDL execution was not in auto-commit mode; the Connection 'local transaction' will be committed and the Connection will be set into auto-commit mode.
Sep 01, 2016 3:51:18 AM org.hibernate.tool.schema.internal.ExceptionHandlerLoggedImpl handleException
WARN: GenerationTarget encountered exception accepting command : Error executing DDL via JDBC Statement
org.hibernate.tool.schema.spi.CommandAcceptanceException: Error executing DDL via JDBC Statement
    at org.hibernate.tool.schema.internal.exec.GenerationTargetToDatabase.accept(GenerationTargetToDatabase.java:62)
    at org.hibernate.tool.schema.internal.SchemaDropperImpl.applySqlString(SchemaDropperImpl.java:374)
    at org.hibernate.tool.schema.internal.SchemaDropperImpl.applySqlStrings(SchemaDropperImpl.java:359)
    at org.hibernate.tool.schema.internal.SchemaDropperImpl.dropFromMetadata(SchemaDropperImpl.java:241)
    at org.hibernate.tool.schema.internal.SchemaDropperImpl.performDrop(SchemaDropperImpl.java:154)
    at org.hibernate.tool.schema.internal.SchemaDropperImpl.doDrop(SchemaDropperImpl.java:126)
    at org.hibernate.tool.schema.internal.SchemaDropperImpl.doDrop(SchemaDropperImpl.java:112)
    at org.hibernate.tool.schema.spi.SchemaManagementToolCoordinator.performDatabaseAction(SchemaManagementToolCoordinator.java:137)
    at org.hibernate.tool.schema.spi.SchemaManagementToolCoordinator.process(SchemaManagementToolCoordinator.java:65)
    at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:307)
    at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:490)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:710)
    at org.sf.main.SessionFactoryBuilder.getSessionFactory(SessionFactoryBuilder.java:26)
    at org.sf.main.SessionFactoryBuilder.main(SessionFactoryBuilder.java:36)
Caused by: java.sql.SQLSyntaxErrorException: ORA-00942: table or view does not exist

    at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:447)
    at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:396)
    at oracle.jdbc.driver.T4C8Oall.processError(T4C8Oall.java:951)
    at oracle.jdbc.driver.T4CTTIfun.receive(T4CTTIfun.java:513)
    at oracle.jdbc.driver.T4CTTIfun.doRPC(T4CTTIfun.java:227)
    at oracle.jdbc.driver.T4C8Oall.doOALL(T4C8Oall.java:531)
    at oracle.jdbc.driver.T4CStatement.doOall8(T4CStatement.java:195)
    at oracle.jdbc.driver.T4CStatement.executeForRows(T4CStatement.java:1036)
    at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:1336)
    at oracle.jdbc.driver.OracleStatement.executeInternal(OracleStatement.java:1916)
    at oracle.jdbc.driver.OracleStatement.execute(OracleStatement.java:1878)
    at oracle.jdbc.driver.OracleStatementWrapper.execute(OracleStatementWrapper.java:318)
    at org.hibernate.tool.schema.internal.exec.GenerationTargetToDatabase.accept(GenerationTargetToDatabase.java:49)
    ... 13 more

这是我的代码 -

    public static SessionFactory getSessionFactory() {
            Configuration configuration = new Configuration();

            configuration.setProperty("hibernate.hbm2ddl.auto", "create");
            configuration.setProperty("hibernate.dialect", "org.hibernate.dialect.Oracle10gDialect");
            configuration.setProperty("hibernate.connection.driver_class", "oracle.jdbc.driver.OracleDriver");
            configuration.setProperty("hibernate.connection.url", "jdbc:oracle:thin:@somehost:1521:orcl");
            configuration.setProperty("hibernate.connection.username", "username");
            configuration.setProperty("hibernate.connection.password", "password");
            configuration.setProperty("show_sql", "true");
            configuration.setProperty("hibernate.default_schema", "somechema");
            configuration.setPhysicalNamingStrategy(new HelloWorldNamingStrategy());
            configuration.addAnnotatedClass(Census2010.class);

            StandardServiceRegistryBuilder builder = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties());
            SessionFactory sessionFactory = configuration.buildSessionFactory(builder.build()); 

            return sessionFactory;
        }

        public static void main (String[] args) {
            Census2010 obj = new Census2010();
            obj.setData(100000L);
            obj.setVariable("Population");

            SessionFactory factory = getSessionFactory();
            Session session = factory.openSession();
            session.beginTransaction();
            session.save(obj);
            session.getTransaction().commit();

            factory.close();

        }

这是我的实体类 -

    import javax.persistence.Column;

    import javax.persistence.Entity;
    import javax.persistence.Id;
    import javax.persistence.Table;

    @Entity
    @Table
    public class Census2010 {
        @Id
        @Column(name="VARIABLE")
        private String variable;

        @Column(name="DATA")
        private long data;

        public String getVariable() {
            return variable;
        }

        public void setVariable(String variable) {
            this.variable = variable;
        }

        public long getData() {
            return data;
        }

        public void setData(long data) {
            this.data = data;
        }
    }

这是NamingStrategy类 -

import org.hibernate.boot.model.naming.Identifier;
import org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl;
import org.hibernate.engine.jdbc.env.spi.JdbcEnvironment;

public class HelloWorldNamingStrategy extends PhysicalNamingStrategyStandardImpl {

    private static final long serialVersionUID = 1L;

    private static final String tableName = "A_12345_P";

    @Override
     public Identifier toPhysicalTableName(Identifier name, JdbcEnvironment context) {
         return new Identifier(tableName, true);
     }
}

感谢任何帮助。

Answer 1

在hibernate.cfg.xml文件中将hbm2ddl.auto属性设置为true时，您要求Hibernate框架创建与您尝试保存的对象相对应的所有表，然后保存对象。

但是，在创建表之前，hibernate首先尝试删除表，假设它们存在于数据库中。

因此，当您第一次运行应用程序时，由于表格不存在于数据库中，您将面临错误。当你下次运行你的程序时，你不会看到上面的错误，因为表存在并且hibernate将能够成功地删除它们。

Answer 2

你确定＆＃34; somechema＆＃34;在句子中configuration.setProperty("hibernate.default_schema", "somechema");是正确的shema？

如果找不到正确的表或视图。

另一个选项是使用注释，示例

@Table(schema = "YOURSCHEMA", name = "Census2010")

了解更多信息https://docs.jboss.org/jbossas/jboss4guide/r2/html/ch13.html

Hibernate - 表或视图不存在错误

2 个答案: