Question

我测试了Hibernate hbm2ddl.auto = update hibernate属性。实际上，如果它没有在数据库中找到表，它会创建表，但如果我在我的pojo类中添加一个字段，它不会改变表。以下是config，mapping，pojo和test java文件。我的Pojo课程，

package beans;
public class Student {
    private int sid;
    private String name;
    private int marks;
    private String email;

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public Student() {
        // TODO Auto-generated constructor stub
    }

    public int getSid() {
        return sid;
    }

    public void setSid(int sid) {
        this.sid = sid;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getMarks() {
        return marks;
    }

    public void setMarks(int marks) {
        this.marks = marks;
    }

}

配置：

<?xml version='1.0' encoding='UTF-8'?>  
<!DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
    "http://www.hibernate.org/dtd/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://localhost:3306/</property>
    <property name="connection.username">xxx</property>
    <property name="connection.password">xxxx</property>
    <property name="connection.pool_size">10</property>
    <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
    <property name="hbm2ddl.auto">update</property>  
    <property name="show_sql">true</property>
    <mapping resource="resources/student.hbm.xml"/>

    </session-factory>
    </hibernate-configuration>

映射：

<?xml version='1.0' encoding='UTF-8'?>  
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
    <hibernate-mapping>
    <class name="beans.Student" table="student" schema="hibernate">
    <id name="sid" ></id>
    <property name="name" />
    <property name="marks" />
    <property name="email" />
    </class>
    </hibernate-mapping>

测试类：

package test;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
public class Client {

    public static void main(String[] args) {

        // Student object state is transiant

        Configuration cfg=new Configuration();

        cfg.configure("resources/hibernate.cfg.xml");

        SessionFactory sf= cfg.buildSessionFactory();

    }
}

如果我删除了表并重新创建然后它创建了具有电子邮件ID的表，但如果我只从表中删除电子邮件字段然后再次运行它不会改变Mysql数据库中的电子邮件字段表。请让我知道出了什么问题？并在eclipse控制台而不是改变它显示创建表语句。例如：ERROR: HHH000388: Unsuccessful: create table hibernate.student (sid integer not null, name varchar(255), marks integer, email varchar(255), rank integer, primary key (sid))

Hibernate hbm2ddl.auto = update不会改变表

0 个答案: