1、SQL

DROP TABLE IF EXISTS `tb_dept`;
CREATE TABLE `tb_dept`  (
  `deptno` tinyint(2) UNSIGNED NOT NULL  COMMENT '部门编号',
  `dname` varchar(14) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '部门名称',
  `loc` varchar(13) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '部门地址',
  PRIMARY KEY (`deptno`) USING BTREE
) ENGINE = InnoDB  CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

INSERT INTO `tb_dept` VALUES (10, 'ACCOUNTING', 'NEW YORK');
INSERT INTO `tb_dept` VALUES (20, 'RESEARCH', 'DALLAS');
INSERT INTO `tb_dept` VALUES (30, 'SALES', 'CHICAGO');
INSERT INTO `tb_dept` VALUES (40, 'OPERATIONS', 'BOSTON');

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DROP TABLE IF EXISTS `tb_emp`;
CREATE TABLE `tb_emp`  (
  `empno` int(4) UNSIGNED NOT NULL,
  `ename` varchar(10) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  `job` varchar(9) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  `mgr` int(4) UNSIGNED  NULL DEFAULT NULL,
  `hiredate` date NULL DEFAULT NULL,
  `sal` decimal(7, 2) NULL DEFAULT NULL,
  `comm` decimal(7, 2) NULL DEFAULT NULL,
  `deptno` tinyint(2) UNSIGNED NULL DEFAULT NULL,
  PRIMARY KEY (`empno`) USING BTREE,
  INDEX `deptno`(`deptno`) USING BTREE,
  CONSTRAINT `tb_emp_ibfk_1` FOREIGN KEY (`deptno`) REFERENCES `tb_dept` (`deptno`) ON DELETE RESTRICT ON UPDATE RESTRICT
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

INSERT INTO `tb_emp` VALUES (7369, 'SMITH', 'CLERK', 7902, '1980-12-17', 800.00, NULL, 20);
INSERT INTO `tb_emp` VALUES (7499, 'ALLEN', 'SALESMAN', 7698, '1981-02-20', 1600.00, 300.00, 30);
INSERT INTO `tb_emp` VALUES (7521, 'WARD', 'SALESMAN', 7698, '1981-02-22', 1250.00, 500.00, 30);
INSERT INTO `tb_emp` VALUES (7566, 'JONES', 'MANAGER', 7839, '1981-04-02', 2975.00, NULL, 20);
INSERT INTO `tb_emp` VALUES (7654, 'MARTIN', 'SALESMAN', 7698, '1981-09-28', 1250.00, 1400.00, 30);
INSERT INTO `tb_emp` VALUES (7698, 'BLAKE', 'MANAGER', 7839, '1981-05-01', 2850.00, NULL, 30);
INSERT INTO `tb_emp` VALUES (7782, 'CLARK', 'MANAGER', 7839, '1981-06-09', 2450.00, NULL, 10);
INSERT INTO `tb_emp` VALUES (7788, 'SCOTT', 'ANALYST', 7566, '1987-04-19', 3000.00, NULL, 20);
INSERT INTO `tb_emp` VALUES (7839, 'KING', 'PRESIDENT', NULL, '1981-11-17', 5000.00, NULL, 10);
INSERT INTO `tb_emp` VALUES (7844, 'TURNER', 'SALESMAN', 7698, '1981-09-08', 1500.00, 0.00, 30);
INSERT INTO `tb_emp` VALUES (7876, 'ADAMS', 'CLERK', 7788, '1987-05-23', 1100.00, NULL, 20);
INSERT INTO `tb_emp` VALUES (7900, 'JAMES', 'CLERK', 7698, '1981-12-03', 950.00, NULL, 30);
INSERT INTO `tb_emp` VALUES (7902, 'FORD', 'ANALYST', 7566, '1981-12-03', 3000.00, NULL, 20);
INSERT INTO `tb_emp` VALUES (7934, 'MILLER', 'CLERK', 7782, '1982-01-23', 1300.00, NULL, 10);

2、实体类

2.1、Dept.java

/**
 * 部门
 * @author HC
 *
 */
public class Dept {
    /**
     * 部门编号
     */
    private Integer deptno;
    /**
     * 部门名称
     */
    private String dname;
    /**
     * 部门地址
     */
    private String loc;

    public Dept() {
    }

    public Dept(Integer deptno, String dname, String loc) {
        this.deptno = deptno;
        this.dname = dname;
        this.loc = loc;
    }

    public Integer getDeptno() {
        return deptno;
    }

    public void setDeptno(Integer deptno) {
        this.deptno = deptno;
    }

    public String getDname() {
        return dname;
    }

    public void setDname(String dname) {
        this.dname = dname;
    }

    public String getLoc() {
        return loc;
    }

    public void setLoc(String loc) {
        this.loc = loc;
    }

    @Override
    public String toString() {
        return "Dept{" +
                "deptno=" + deptno +
                ", dname='" + dname + '\'' +
                ", loc='" + loc + '\'' +
                '}';
    }
}

2.2、Emp.java

/**
 * 员工
 * @author HC
 */
public class Emp {
    /**
     * 员工编号
     */
    private Integer empno;
    /**
     * 员工姓名
     */
    private String ename;
    /**
     * 工作
     */
    private String job;
    /**
     * 上级领导编号
     */
    private Integer mgr;
    /**
     * 受雇日期
     */
    private LocalDate hiredate;
    /**
     * 薪资
     */
    private Double sal;
    /**
     * 奖金
     */
    private Double comm;
    /**
     * 部门编号
     */
    private Integer deptno;

    public Emp() {
    }

    public Emp(Integer empno, String ename, String job, Integer mgr, LocalDate hiredate, Double sal, Double comm, Integer deptno) {
        this.empno = empno;
        this.ename = ename;
        this.job = job;
        this.mgr = mgr;
        this.hiredate = hiredate;
        this.sal = sal;
        this.comm = comm;
        this.deptno = deptno;
    }

    public Integer getEmpno() {
        return empno;
    }

    public void setEmpno(Integer empno) {
        this.empno = empno;
    }

    public String getEname() {
        return ename;
    }

    public void setEname(String ename) {
        this.ename = ename;
    }

    public String getJob() {
        return job;
    }

    public void setJob(String job) {
        this.job = job;
    }

    public Integer getMgr() {
        return mgr;
    }

    public void setMgr(Integer mgr) {
        this.mgr = mgr;
    }

    public LocalDate getHiredate() {
        return hiredate;
    }

    public void setHiredate(LocalDate hiredate) {
        this.hiredate = hiredate;
    }

    public Double getSal() {
        return sal;
    }

    public void setSal(Double sal) {
        this.sal = sal;
    }

    public Double getComm() {
        return comm;
    }

    public void setComm(Double comm) {
        this.comm = comm;
    }

    public Integer getDeptno() {
        return deptno;
    }

    public void setDeptno(Integer deptno) {
        this.deptno = deptno;
    }

    @Override
    public String toString() {
        return "Emp{" +
                "empno=" + empno +
                ", ename='" + ename + '\'' +
                ", job='" + job + '\'' +
                ", mgr=" + mgr +
                ", hiredate=" + hiredate +
                ", sal=" + sal +
                ", comm=" + comm +
                ", deptno=" + deptno +
                '}';
    }
}

3、数据库模拟代码

public class DB {
    private static List<Emp> emps = new ArrayList<>();
    private static List<Dept> depts = new ArrayList<>();

    static {
        depts.add(new Dept(10,"ACCOUNTING","NEWYORK"));
        depts.add(new Dept(20,"RESEARCH","DALLAS"));
        depts.add(new Dept(30,"SALES","CHICAGO"));
        depts.add(new Dept(40,"OPERATIONS","BOSTON"));

        emps.add(new Emp(7369, "SMITH", "CLERK", 7902,LocalDate.of(1980, 12, 17), 800D, null, 20));
        emps.add(new Emp(7499, "ALLEN", "SALESMAN", 7698, LocalDate.of(1981, 2, 20), 1600D, 300D, 30));
        emps.add(new Emp(7521, "WARD", "SALESMAN", 7698, LocalDate.of(1981, 2, 22), 1250D, 500D, 30));
        emps.add(new Emp(7566, "JONES", "MANAGER", 7893, LocalDate.of(1981, 4, 2), 2975D, null, 20));
        emps.add(new Emp(7654, "MARTIN", "SALESMAN", 7698, LocalDate.of(1981, 9, 28), 1250D, 1400D, 30));
        emps.add(new Emp(7698, "BLAKE", "MANAGER", 7839, LocalDate.of(1981, 5, 1), 2850D, null, 30));
        emps.add(new Emp(7782, "CLARK", "MANAGER", 7839, LocalDate.of(1981, 6, 9), 2450D, 600D, 10));
        emps.add(new Emp(7788, "SCOTT", "ANALYST", 7566, LocalDate.of(1987, 4, 19), 3000D, null, 20));
        emps.add(new Emp(7839, "KING", "PRESIDENT", null, LocalDate.of(1981, 11, 17), 5000D, null, 10));
        emps.add(new Emp(7844, "TURNER", "SALESMAN", 7698, LocalDate.of(1981, 9, 8), 1500D, null, 30));
        emps.add(new Emp(7876, "ADAMS", "CLERK", 7788, LocalDate.of(1987, 5, 23), 1100D, 350D, 20));
        emps.add(new Emp(7900, "JAMES", "CLERK", 7698, LocalDate.of(1981, 12, 3), 950D, null, 30));
        emps.add(new Emp(7902, "FORD", "ANALYST", 7566, LocalDate.of(1981, 12, 3), 3000D, null, 20));
        emps.add(new Emp(7934, "MILLER", "CLERK", 7782, LocalDate.of(1982, 1, 23), 1300D, 400D, 10));
    }

    public static List<Emp> getEmps() {
        return emps;
    }

    public static List<Dept> getDepts() {
        return depts;
    }
}