Java Hibernate hbm2ddl.auto=更新不会改变表
我测试了Hibernate hbm2ddl.auto=updatehibernate属性。实际上,如果在数据库中找不到该表,它就会创建该表,但如果我在pojo类中再添加一个字段,它就不会更改该表。下面是配置、映射、pojo和测试java文件。 我的Pojo班Java Hibernate hbm2ddl.auto=更新不会改变表,java,mysql,hibernate,Java,Mysql,Hibernate,我测试了Hibernate hbm2ddl.auto=updatehibernate属性。实际上,如果在数据库中找不到该表,它就会创建该表,但如果我在pojo类中再添加一个字段,它就不会更改该表。下面是配置、映射、pojo和测试java文件。 我的Pojo班 package beans; public class Student { private int sid; private String name; private int marks; private S
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>
如果我删除表并重新创建,那么它将创建具有电子邮件id的表,但如果我仅从表中删除电子邮件字段,然后再次运行,则不会更改Mysql数据库中具有电子邮件字段的表。请告诉我出了什么问题?并在eclipse控制台中显示CREATETABLE语句,而不是alter语句。例如:
错误:HHH000388:不成功:创建表hibernate.student(sid integer非空,名称varchar(255),marks integer,email varchar(255),rank integer,主键(sid))
我发现hibernate.hbm2ddl.auto“value=”update将添加一个db列,该列在共享链接位置的位置不存在。已使用id、名称和标记创建了表。该表存在于数据库中。现在,电子邮件字段必须与表一起添加。如果我在pojo类中使用update和addingemail字段,理想情况下它应该用email字段修改表,对吗?但它不会改变桌子。
<?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>
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();
}
}