查询表中的所有雇员信息，以及查询每个员工的部门信息和领导信息

注意看返回值的类型

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package testdemo;

 
/**
 *
 * @author Jone
 */

    
    
    class emp{
        private int empno;
        private String ename;
        private String job;
        private double sal;
        private double comm;
        private emp mgr;
        private Dept dept;
        public emp(){};
        public emp(int empno, String ename, String job, double sal, double comm){
            this.empno = empno;
            this.job = job;
            this.comm = comm;
            this.ename = ename;
            this.sal = sal;
        }
        public void setMgr(emp mgr){
            this.mgr  = mgr;
        }
        public emp getMgr(){
            return this.mgr;
        }
        public void setDept(Dept dept){
            this.dept  = dept;
        }
        public Dept getDept(){
            return this.dept;
        }
        public void  setEmpno(int empno){
            this.empno = empno;
        }
        public void setEname(String ename)
        {
            this.ename = ename;
        }        
        public void setJob(String job){
            this.job = job;
        }
        public void setSal (double sal){
            this.sal = sal;
        }
        public void setComm (double comm){
            this.comm = comm;
        }
        public int getEmpno(){
            return this.empno;
        }
        public String getEname(){
            return this.ename;
        }
        public String getJob(){
            return this.job;
        }
        public double getSal(){
            return this.sal;
        }
        public double getComm(){
            return this.comm;
        }
        public String getEmpInfo(){
            return "empno = "+ this.empno +
                    "ename = "+ this.ename +
                    "job = "+ this.sal +
                    "sal = " + this.comm ;
        }
    }
    
    class Dept{
        private int deptno;
        private String dname;
        private String loc;
        private emp [] Emps;
        
        public Dept(){}
        public Dept(int deptno, String dname, String loc){
            this.deptno = deptno;
            this.dname = dname;
            this.loc = loc;
        }
        public void setEmps(emp [] Emps){
            this.Emps = Emps;
        }
        public emp[] getEmps(){
            return this.Emps;
        }
        public void setDeptno(int deptno){
            this.deptno = deptno;
        }
        public void setDnama(String dname){
            this.dname = dname;
        }
        public void setLoc(String loc){
            this.loc  = loc;
        }
        
        public int getDeptno(){
            return this.deptno;
        }
        public String getDname(){
            return this.dname;
        }
        public String getLoc(){
            return this.loc;
        }
        public String gerDeptInfo(){
            return "deptno = "+ this.deptno +
                    "dname = "+ this.dname +
                    "lco = " + this.loc;
        }
        
    }
 public class TestDemo {
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        //第一步设置类对象间的关系
        //1. 分别创建各自类的对象
        Dept dept = new Dept(10,"Accontiing ", "Newyork");
        emp ea = new emp(7369, "smith", "clerck", 800.0, 0.0);
        emp eb = new emp(7366, "allen", "manager", 2450.0, 0.0);
        emp ec = new emp(7777, "king", "preseident", 5000.0,0.0);
        //2. 设置雇员的关系
            ea.setMgr(eb);
            eb.setMgr(ec);
            //3设置雇员和部门的关系
           ea.setDept(dept);
           eb.setDept(dept);
           ec.setDept(dept);
           //3设置部门与雇员的关系
           dept.setEmps(new emp[] {ea,eb,ec});
        //第二步进行数据的取得
        //输出一部门的全部雇员
        System.out.println(dept.gerDeptInfo());
        for(int i=0; i<dept.getEmps().length; i++)
        {
            System.out.println(dept.getEmps() [i].getEmpInfo());
             if(dept.getEmps()[i].getMgr() != null)   //输出雇员的领导
                System.out.println(dept.getEmps() [i].getMgr().getEmpInfo());
        }
        System.out.println("=======================\n");
        System.out.println(ea.getEmpInfo());
        if(ea.getMgr() != null)
            System.out.println(ea.getMgr().getEmpInfo());
       if(ea.getDept() != null)
           System.out.println(ea.getDept().gerDeptInfo());
    }        
 }