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Question

I want to know, that if we have two class :

1) Employee.java

2) PermanentEmployee.java

Now, I want to know:

1. if there exists a record with `id = 1` in Employee table.
2. id generator used in increment.
3. There is no record in PermanentEmployee table.
4. Is it possible to insert a record with id 1 in PermanentEmployee table 

ie if we save record of `permanentEmployee`, than a new record should get insert in `permannentEmployee` table and it should refer to already existing record in Employee table ?

Any pointers will be of great help 


More Description :

Employee.java 
----------------------------
package com.kar.hibernate;

public class Employee {

    private int eid;
    private String ename;
    private String ecity;
    private String eemail;
    private Long ephone;
    public Employee() {
        super();
    }
    public Employee(String ename, String ecity, String eemail, Long ephone) {
        super();
        this.ename = ename;
        this.ecity = ecity;
        this.eemail = eemail;
        this.ephone = ephone;
    }
    public int getEid() {
        return eid;
    }
    public void setEid(int eid) {
        this.eid = eid;
    }
    public String getEname() {
        return ename;
    }
    public void setEname(String ename) {
        this.ename = ename;
    }
    public String getEcity() {
        return ecity;
    }
    public void setEcity(String ecity) {
        this.ecity = ecity;
    }
    public String getEemail() {
        return eemail;
    }
    public void setEemail(String eemail) {
        this.eemail = eemail;
    }
    public Long getEphone() {
        return ephone;
    }
    public void setEphone(Long ephone) {
        this.ephone = ephone;
    }
    @Override
    public String toString() {
        return "Employee [eid=" + eid + ", ename=" + ename + ", ecity=" + ecity
                + ", eemail=" + eemail + ", ephone=" + ephone + "]";
    }


}
-----------------------------------------------
OldEmployee.java
-----------------------------------------------
package com.kar.hibernate;

public class OldEmployee extends Employee{

    private String oeDateOfRelease;
    private int oeDurationInCompany;

    public OldEmployee() {
    }

    public OldEmployee(String ename, String ecity, String eemail, Long ephone
            ,String oeDateOfRelease, int oeDurationInCompany) {
        super(ename, ecity, eemail, ephone);
        this.oeDateOfRelease=oeDateOfRelease;
        this.oeDurationInCompany=oeDurationInCompany;
    }

    public String getOeDateOfRelease() {
        return oeDateOfRelease;
    }

    public void setOeDateOfRelease(String oeDateOfRelease) {
        this.oeDateOfRelease = oeDateOfRelease;
    }

    public int getOeDurationInCompany() {
        return oeDurationInCompany;
    }

    public void setOeDurationInCompany(int oeDurationInCompany) {
        this.oeDurationInCompany = oeDurationInCompany;
    }

    @Override
    public String toString() {
        return super.toString()+":::::"+ "OldEmployee [oeDateOfRelease=" + oeDateOfRelease
                + ", oeDurationInCompany=" + oeDurationInCompany + "]";
    }

}
=================================================
Client1.java
=================================================
package com.kar.hibernate;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.classic.Session;

public class Client1 {
    public static void main(String[] args) {
        Transaction tx=null;
        try
        {
            SessionFactory sessionFactory=CHibernateUtil.getSessionFactory();
            Session session=sessionFactory.openSession();
            tx=session.beginTransaction();

            String ename="anuj";
            String ecity="blore";
            String eemail="a@a";
            Long ephone=1111l;

            Employee e=new Employee(ename, ecity, eemail, ephone);
            session.save(e);

            tx.commit();
            session.close();
        }
        catch(Exception e)
        {
            e.printStackTrace();
            if(tx!=null)
                tx.rollback();
        }
    }
}

===================================================================
Client2.java
==========================================
package com.kar.hibernate;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.classic.Session;
import org.hibernate.event.SaveOrUpdateEvent;

public class Client2{
    public static void main(String[] args) {
        Transaction tx=null;
        try
        {
            SessionFactory sessionFactory=CHibernateUtil.getSessionFactory();
            Session session=sessionFactory.openSession();
            tx=session.beginTransaction();

            Employee e=(Employee)session.load(Employee.class, 1);


            OldEmployee oe=new OldEmployee(e.getEname(),
                    e.getEcity(), e.getEemail(), 
e.getEphone(), "1/1/2014", 2);

            session.saveOrUpdate(oe);

            tx.commit();
            session.close();
        }
        catch(Exception e)
        {
            e.printStackTrace();
            if(tx!=null)
                tx.rollback();
        }
    }
}

-------------------------------------------------------------------
Employee.hbm.xml
---------------------------------------------------------------------
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >
<hibernate-mapping package="com.kar.hibernate">

<class name="Employee" table="employee">
<id name="eid" column="eid" type="int">
<generator class="increment"/>
</id>
<property name="ename" column="ename" type="string"/>
<property name="ecity" column="ecity" type="string"/>
<property name="eemail" column="email"/>
<property name="ephone"/>

<joined-subclass name="OldEmployee" table="oldEmployee">
<key column="eid"></key>
<property name="oeDateOfRelease"></property>
<property name="oeDurationInCompany"></property>
</joined-subclass>

</class>
</hibernate-mapping>

====================================================================
Hibernate.cfg.xml
===================================================================
<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
          "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
          "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
    <session-factory>
    <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/chm</property>
            <property name="hibernate.connection.username">root</property>
                <property name="hibernate.connection.password">root</property>

          <property name="dialect">org.hibernate.dialect.MySQLDialect</property>           
  <property name="hibernate.hbm2ddl.auto">update</property>           
     <property name="show_sql">true</property>   
    <mapping resource="com/kar/hibernate/Employee.hbm.xml"/>

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

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============ //现在我的问题是在Client2中编辑什么，所以当我们尝试保存OldEmployee时不应在Employee表中插入新记录。但OldEmployee表的新记录应该引用现有的Employee Table记录？

任何指针都会有很大的帮助。

Answer 1

每个子类的继承表就是这种情况，hibernate documentation.

你的问题，无法像你想象的那样解决。首先，不能以常规方式完成java或hibernate。所以你的选择是;

删除原始Employee并插入新的OldEmployee对象
手动插入旧员工对象。 session.createSQLQuery("insert into oldEmployee values (employeeId, ....)")

正如您所看到的，这两种解决方案都是解决方法，也许重新检查您的继承甚至业务模型会更聪明。

每个子类映射的Hibernate表

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1 个答案: