一、数据库的emp名和dept表
建立持久化类和配置文件，可以用MyEclipse直接生成
持久化类
package entity;
import java.util.Date;
public class Emp implements java.io.Serializable {
// Fields
private Short empno;
private Dept dept;
private String ename;
private String job;
private Short mgr;
private Date hiredate;
private Double sal;
private Double comm;
// Constructors
/** default constructor */
public Emp() {
}
/** minimal constructor */
public Emp(Short empno) {
this.empno = empno;
}
/** full constructor */
public Emp(Short empno, Dept dept, String ename, String job, Short mgr,
Date hiredate, Double sal, Double comm) {
this.empno = empno;
this.dept = dept;
this.ename = ename;
this.job = job;
this.mgr = mgr;
this.hiredate = hiredate;
this.sal = sal;
this.comm = comm;
}
// Property accessors
public Short getEmpno() {
return this.empno;
}
public void setEmpno(Short empno) {
this.empno = empno;
}
public Dept getDept() {
return this.dept;
}
public void setDept(Dept dept) {
this.dept = dept;
}
public String getEname() {
return this.ename;
}
public void setEname(String ename) {
this.ename = ename;
}
public String getJob() {
return this.job;
}
public void setJob(String job) {
this.job = job;
}
public Short getMgr() {
return this.mgr;
}
public void setMgr(Short mgr) {
this.mgr = mgr;
}
public Date getHiredate() {
return this.hiredate;
}
public void setHiredate(Date hiredate) {
this.hiredate = hiredate;
}
public Double getSal() {
return this.sal;
}
public void setSal(Double sal) {
this.sal = sal;
}
public Double getComm() {
return this.comm;
}
public void setComm(Double comm) {
this.comm = comm;
}
}
Emp持久化类
package entity;
import java.util.HashSet;
import java.util.Set;
public class Dept implements java.io.Serializable {
// Fields
private Byte deptno;
private String dname;
private String loc;
private Set emps = new HashSet(0);
// Constructors
/** default constructor */
public Dept() {
}
/** minimal constructor */
public Dept(Byte deptno) {
this.deptno = deptno;
}
/** full constructor */
public Dept(Byte deptno, String dname, String loc, Set emps) {
this.deptno = deptno;
this.dname = dname;
this.loc = loc;
this.emps = emps;
}
// Property accessors
public Byte getDeptno() {
return this.deptno;
}
public void setDeptno(Byte deptno) {
this.deptno = deptno;
}
public String getDname() {
return this.dname;
}
public void setDname(String dname) {
this.dname = dname;
}
public String getLoc() {
return this.loc;
}
public void setLoc(String loc) {
this.loc = loc;
}
public Set getEmps() {
return this.emps;
}
public void setEmps(Set emps) {
this.emps = emps;
}
}
Dept持久化类
emp类配置文件
<?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>
<class name="entity.Emp" table="EMP" schema="SCOTT">
<id name="empno" type="java.lang.Short">
<column name="EMPNO" precision="4" scale="0" />
<generator class="assigned" />
</id>
<many-to-one name="dept" class="entity.Dept" fetch="select">
<column name="DEPTNO" precision="2" scale="0" />
</many-to-one>
<property name="ename" type="java.lang.String">
<column name="ENAME" length="10" />
</property>
<property name="job" type="java.lang.String">
<column name="JOB" length="9" />
</property>
<property name="mgr" type="java.lang.Short">
<column name="MGR" precision="4" scale="0" />
</property>
<property name="hiredate" type="java.util.Date">
<column name="HIREDATE" length="7" />
</property>
<property name="sal" type="java.lang.Double">
<column name="SAL" precision="7" />
</property>
<property name="comm" type="java.lang.Double">
<column name="COMM" precision="7" />
</property>
</class>
</hibernate-mapping>
Emp.hbm.xml
dept类配置文件
<?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>
<class name="entity.Dept" table="DEPT" schema="SCOTT">
<id name="deptno" type="java.lang.Byte">
<column name="DEPTNO" precision="2" scale="0" />
<generator class="assigned" />
</id>
<property name="dname" type="java.lang.String">
<column name="DNAME" length="14" />
</property>
<property name="loc" type="java.lang.String">
<column name="LOC" length="13" />
</property>
<set name="emps" inverse="true">
<key>
<column name="DEPTNO" precision="2" scale="0" />
</key>
<one-to-many class="entity.Emp" />
</set>
</class>
</hibernate-mapping>
Dept.hbm.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="dialect">
org.hibernate.dialect.Oracle9Dialect
</property>
<property name="connection.url">
jdbc:oracle:thin:@localhost:1521:orcl
</property>
<property name="connection.username">root</property>
<property name="connection.password">root</property>
<property name="connection.driver_class">
oracle.jdbc.OracleDriver
</property>
<mapping resource="entity/Emp.hbm.xml" />
<mapping resource="entity/Dept.hbm.xml" />
</session-factory>
</hibernate-configuration>
hibernate.cfg.xml
二、Query接口分页实现
- 根据结果获得总亡录数：
Querty query=session.createQuery("from Emp");
List list=query.list();
int count=list.size();
- 计算总页数：
int totalPages=(count%pageSize==0)?(count/pageSize):(count/pageSize+1);
- 实现分页：
query.setFirstResult((pageIndex-1)*pageSize); //开始记录数 query.setMaxResults(pageSize);//每页显示最大记录数 List resultList=query.list(); //每页显示的记录集合
查询全部员工
/*
* 查询员工表内容
*/
public static void findEmp(){
Session session=new Configuration().configure().buildSessionFactory().openSession();
//查询员工表按入职日期升序排，日期相同按名字降序
String hql=" from Emp e order by e.hiredate ,e.ename desc ";
Query query=session.createQuery(hql);
List<Emp> emps=query.list();
for (Emp emp : emps) {
System.out.println("员工编号："+emp.getEmpno()+"\t姓名： "+emp.getEname()+"\t入职日期："+emp.getHiredate()+"\t部门名称："+emp.getDept().getDname());
}
}
分页查询
/*
* 分页查询
*/
public static void pageDisplay(){
Session session=new Configuration().configure().buildSessionFactory().openSession();
String hql="from Emp";
//第几页
int pageIndex=4;
//每页显示记录数
int pageSize=4;
Query query=session.createQuery(hql);
//起始记录数
query.setFirstResult((pageIndex-1)*pageSize);
//每页显示最多记录数
query.setMaxResults(pageSize);
List<Emp> emps=query.list();
for (Emp emp : emps) {
System.out.println("员工编号："+emp.getEmpno()+"\t姓名： "+emp.getEname()+"\t入职日期："+emp.getHiredate()+"\t部门名称："+emp.getDept().getDname());
}
}
三、连接查询
部门表中有个40部门，员工表中没有人是40部门的，
首先向EMP表中插入一条没有部门的记录
insert into emp(empno,ename,job,hiredate,sal)values(8888,‘张三‘,‘业务员‘,sysdate,800);
3.1、查询部门的所有员工使用内连接
String hql="from Dept d inner join d.emps";
3.2、查询部门的所有员工使用左外连接
String hql="from Dept d left join d.emps";
3.3、查询部门的所有员工使用右外连接
String hql="from Dept d right join d.emps";
时间： 2024-12-13 08:23:25