Hibernate:根据实体类自动创建/更新数据库表 [英] Hibernate: Automatically creating/updating the db tables based on entity classes

问题描述

我有以下实体类(在 Groovy 中):

I have the following entity class (in Groovy):

import javax.persistence.Entity
import javax.persistence.Id
import javax.persistence.GeneratedValue
import javax.persistence.GenerationType

@Entity
public class ServerNode {

  @Id
  @GeneratedValue(strategy = GenerationType.AUTO)
  Long id

  String firstName
  String lastName

}

和我的persistence.xml:

and my persistence.xml:

<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence" version="1.0">
    <persistence-unit name="NewPersistenceUnit">
        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <properties>
            <property name="hibernate.connection.url" value="jdbc:mysql://localhost:3306/Icarus"/>
            <property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/>
            <property name="hibernate.connection.username" value="root"/>
            <property name="hibernate.connection.password" value=""/>
            <property name="hibernate.archive.autodetection" value="class"/>
            <property name="hibernate.show_sql" value="true"/>
            <property name="hibernate.format_sql" value="true"/>
            <property name="hbm2ddl.auto" value="create"/>
        </properties>
        <class>net.interaxia.icarus.data.models.ServerNode</class>
    </persistence-unit>
</persistence>

和脚本:

import javax.persistence.EntityManager
import javax.persistence.EntityManagerFactory
import javax.persistence.Persistence
import net.interaxia.icarus.data.models.ServerNode

def factory = Persistence.createEntityManagerFactory("NewPersistenceUnit")
def manager = factory.createEntityManager()

manager.getTransaction().begin()

manager.persist new ServerNode(firstName: "Test", lastName: "Server")

manager.getTransaction().commit()

数据库 Icarus 存在，但目前没有表.我希望 Hibernate 能够根据实体类自动创建和/或更新表.我将如何做到这一点?

the database Icarus exists, but currently has no tables. I would like Hibernate to automatically create and/or update the tables based on the entity classes. How would I accomplish this?

推荐答案

我不知道将 hibernate 放在前面是否会有所不同.

I don't know if leaving hibernate off the front makes a difference.

参考 建议它应该是 hibernate.hbm2ddl.auto

create 的值将在 sessionFactory 创建时创建您的表，并保持它们不变.

A value of create will create your tables at sessionFactory creation, and leave them intact.

create-drop 的值将创建您的表，然后在您关闭 sessionFactory 时删除它们.

A value of create-drop will create your tables, and then drop them when you close the sessionFactory.

也许您应该设置 javax.persistence.Table 显式注解?

Perhaps you should set the javax.persistence.Table annotation explicitly?

希望这会有所帮助.

这篇关于Hibernate:根据实体类自动创建/更新数据库表的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！