JTDS 尝试（但失败了）在应用程序启动时重新创建已经存在的 table

Question

我正在尝试编写一个应用程序来连接到 MS SQL 服务器数据库。数据库已存在，table 已配置。我想要做的就是将我的 Java Spring 应用程序连接到已经存在的服务器。但是，当我尝试这样做时，出现此错误：

Caused by: java.sql.SQLException: There is already an object named 'Customer' in the database.
at net.sourceforge.jtds.jdbc.SQLDiagnostic.addDiagnostic(SQLDiagnostic.java:372) ~[jtds-1.3.1.jar:1.3.1]
at net.sourceforge.jtds.jdbc.TdsCore.tdsErrorToken(TdsCore.java:2988) ~[jtds-1.3.1.jar:1.3.1]
at net.sourceforge.jtds.jdbc.TdsCore.nextToken(TdsCore.java:2421) ~[jtds-1.3.1.jar:1.3.1]
at net.sourceforge.jtds.jdbc.TdsCore.getMoreResults(TdsCore.java:671) ~[jtds-1.3.1.jar:1.3.1]
at net.sourceforge.jtds.jdbc.JtdsStatement.processResults(JtdsStatement.java:613) ~[jtds-1.3.1.jar:1.3.1]
at net.sourceforge.jtds.jdbc.JtdsStatement.executeSQL(JtdsStatement.java:572) ~[jtds-1.3.1.jar:1.3.1]
at net.sourceforge.jtds.jdbc.JtdsStatement.executeImpl(JtdsStatement.java:809) ~[jtds-1.3.1.jar:1.3.1]
at net.sourceforge.jtds.jdbc.JtdsStatement.execute(JtdsStatement.java:1282) ~[jtds-1.3.1.jar:1.3.1]
at org.hibernate.tool.schema.internal.exec.GenerationTargetToDatabase.accept(GenerationTargetToDatabase.java:54) ~[hibernate-core-5.1.10.Final.jar:5.1.10.Final]
... 87 common frames omitted

似乎 JTDS 正在尝试重新创建我的客户 table，实际上如果我删除 table 然后运行应用程序，它确实会创建一个新的 table 在我的数据库中称为 "Customer"。但是，我不能在每次应用程序启动时删除我的 table（出于显而易见的原因），因此我需要配置我的应用程序以连接到已经存在的 table。我该怎么做？

数据库应用程序配置：

@Configuration
@EnableJpaRepositories
@EntityScan("com.example.dbentity")
public class AppConfig {

@Value("${db.driver.class.name}")
private String dbDriverClassName;

@Value("${db.prefix}")
private String dbPrefix;

@Value("${db.url}")
private String dbUrl;

@Value("${db.name}")
private String dbName;

@Value("${db.username}")
private String dbUsername;

@Value("${db.password}")
private String dbPassword;

@Bean
public DataSource DataSource() {
    DriverManagerDataSource dataSource = new DriverManagerDataSource();
    dataSource.setDriverClassName(dbDriverClassName);
    String connectionUrl = dbPrefix + dbUrl + "/" +dbName;
    dataSource.setUrl(connectionUrl);
    dataSource.setUsername(dbUsername);
    dataSource.setPassword(dbPassword);

    return dataSource;
}

@Bean
public JdbcTemplate JdbcTemplate() {
    JdbcTemplate template = new JdbcTemplate();
    template.setDataSource(DataSource());
    return template;
}

@Bean
public EntityManagerFactory entityManagerFactory() {
    HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
    vendorAdapter.setGenerateDdl(true);
    LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();
    factory.setJpaVendorAdapter(vendorAdapter);
    factory.setPackagesToScan("com.example.dbentity");
    factory.setDataSource(DataSource());
    factory.afterPropertiesSet();
    return factory.getObject();
}

@Bean
public PlatformTransactionManager transactionManager() {
    JpaTransactionManager txManager = new JpaTransactionManager();
    txManager.setEntityManagerFactory(entityManagerFactory());
    return txManager;
}
}

配置 YAML：

spring:
  application:
    name: sample-application
  jpa:
    hibernate:
      ddl-auto: validate

server:
  port: 8080
  max-http-header-size: 65536

db:
  driver:
    class:
      name: net.sourceforge.jtds.jdbc.Driver
  prefix: jdbc:jtds:sqlserver://
  url: example-server.net:1433
  name: example-db
  username: user
  password: password

休眠输出：

2018-07-13 10:57:56.831  INFO 15336 --- [           main] o.s.j.d.DriverManagerDataSource          : Loaded JDBC driver: net.sourceforge.jtds.jdbc.Driver
2018-07-13 10:57:56.882  INFO 15336 --- [           main] j.LocalContainerEntityManagerFactoryBean : Building JPA container EntityManagerFactory for persistence unit 'default'
2018-07-13 10:57:56.901  INFO 15336 --- [           main] o.hibernate.jpa.internal.util.LogHelper  : HHH000204: Processing PersistenceUnitInfo [
name: default
...]
2018-07-13 10:57:57.002  INFO 15336 --- [           main] org.hibernate.Version                    : HHH000412: Hibernate Core {5.1.10.Final}
2018-07-13 10:57:57.002  INFO 15336 --- [           main] org.hibernate.cfg.Environment            : HHH000206: hibernate.properties not found
2018-07-13 10:57:57.006  INFO 15336 --- [           main] org.hibernate.cfg.Environment            : HHH000021: Bytecode provider name : javassist
2018-07-13 10:57:57.060  INFO 15336 --- [           main] o.hibernate.annotations.common.Version   : HCANN000001: Hibernate Commons Annotations {5.0.1.Final}
2018-07-13 10:57:57.531  INFO 15336 --- [           main] org.hibernate.dialect.Dialect            : HHH000400: Using dialect: org.hibernate.dialect.SQLServer2012Dialect
2018-07-13 10:57:57.672  INFO 15336 --- [           main] o.h.e.j.e.i.LobCreatorBuilderImpl        : HHH000423: Disabling contextual LOB creation as JDBC driver reported JDBC version [3] less than 4
2018-07-13 10:57:58.754  WARN 15336 --- [           main] o.h.t.s.i.ExceptionHandlerLoggedImpl     : GenerationTarget encountered exception accepting command : Error executing DDL via JDBC Statement

谢谢。

Answer 1

Hibernate 有一个名为 ddl-auto 的属性，您可以在其中设置 Hibernate 是否 create 启动时的架构，validate 已经存在的架构，或者不验证现有架构。

你想做的就是使用validate（或none）。

请参阅 here for how to configure this in Spring Boot and here（即 hibernateProperties）了解如何在 Vanilla Spring 中执行此操作。

JTDS 尝试（但失败了）在应用程序启动时重新创建已经存在的 table

JTDS tries (and fails) to recreate already-existing table on application start

sql-server

spring-data-jpa

jtds