Question

我正在尝试编写SQL SELECT语句，以找出EACH部门中最近雇用的员工。我正在研究Oracle数据库，我正在尝试显示部门名称，员工姓名，雇用日期和薪水。员工和部门表的表定义如下部门表

CREATE TABLE dpt
( DEPARTMENT_ID         NUMBER(4) PRIMARY KEY,
  DEPARTMENT_NAME   VARCHAR2(20) NOT NULL,
  ADDRESS           VARCHAR2(20) NOT NULL);

示例数据

(10, 'ACCOUNTING', 'NEW YORK');
(20, 'RESEARCH', 'DALLAS');
(30, 'SALES', 'CHICAGO');

员工表

CREATE TABLE emp 
( EMPLOYEE_ID   NUMBER(4) PRIMARY KEY,
  EMPLOYEE_NAME VARCHAR2(20) NOT NULL,
  JOB           VARCHAR2(50) NOT NULL,
  MANAGER_ID    NUMBER(4),HIRE_DATE     DATE,
  SALARY        NUMBER(9, 2),
  COMMISSION    NUMBER(9, 2),
  DEPARTMENT_ID NUMBER(4) REFERENCES dpt(DEPARTMENT_ID));

示例数据

 (7839, 'KING',  'PRESIDENT', NULL, '20-NOV-01', 5000, NULL, 50);
 (7596, 'JOST',  'VICE PRESIDENT', 7839, '04-MAY-01', 4500, NULL, 50);
 (7603, 'CLARK', 'VICE PRESIDENT', 7839, '12-JUN-01', 4000, NULL, 50);

我写的查询仅在一个部门中输出雇佣最多的员工。有人可以指出我做错了什么吗？我尝试使用Group By但是无法以正确的方式执行此操作。

SELECT dpt.department_name, dpt.department_id, employee_name, hire_date, Salary 
    from dpt, emp
    where emp.department_id = dpt.department_id
    and
    hire_date = (select max(hire_date) from emp where department_id = emp.department_id)
    order by dpt.department_name;

Answer 1

您缺少相关子查询中where子句的表别名：

SELECT dpt.department_name, dpt.department_id, employee_name, hire_date, Salary 
from dpt join
     emp
     on emp.department_id = dpt.department_id
where hire_date = (select max(hire_date) from emp emp2 where emp.department_id = emp2.department_id)
order by dpt.department_name;

基本上，条件where department_id = emp.department_id从子查询中的表中提取两次列。它与外部查询无关。通过使用适当的表别名，您可以获得相关性。

我还更改了join语法以使用显式连接形式。

Answer 2

您可以通过加入

来完成

SELECT dpt.department_name, dpt.department_id, employee_name, hire_date, Salary 
    from dpt inner join emp on emp.department_id = dpt.department_id inner join
    (select emp.department_id, max(hire_date) as datemax from emp) x on  emp.department_id=x.department_id and emp.hire_date =x.datemax     
    order by dpt.department_name;

Answer 3

您可以尝试这样的事情：

SELECT d.department_name,
       d.department_id,
       e.employee_name,
       e.hire_date,
       e.salary
  FROM dpt d,
  JOIN (SELECT MAX(hire_date) over(PARTITION BY department_id) max_hdate,
               emp.*
          FROM emp) e ON e.department_id = d.department_id
 WHERE e.hire_date = e.max_hdate;

Answer 4

另一个解决方案就是这个：

with t as 
   (SELECT department_name, department_id, employee_name, hire_date, Salary,
      max(hire_date) over (partition by department_id) as max_hire_date
   from dpt join
      join emp using (department_id))
select *
from t
where max_hire_date = hire_date

Answer 5

SELECT employee_id, employee_name, department_id FROM emp e1 WHERE hiredate = (SELECT max(hiredate) FROM emp e2 GROUP BY department_id HAVING e2.department_id=e1.department_id);

Answer 6

Data emp;
Input id name $ dept_no sal  title $ hire_date;
informat hire_date date9.;
Cards;
555  Kearny   200      7000   Manager 08Feb2102
666   williams   100       8000  Manager 30Jan2104
668  Mitchele 100        5000  clerk 14Jul2015 
777  Haberle     200      6000  Clerk 29Jan2001
888  Haberle    200       5000  Clerk 03Feb2015
 890     Johnson     300      4000  Analyst 02Mar2012
889  Dupont     400              5000  clerk  06May2011     .   
  990    McCabe     400       6000  Programmer 10Dec2015
999     Lopez           300           9000  Manager 12dec2105
;
Data Dept;
Input Dept_no  Dept_name $ Dept_city $ Dept_mgr;
cards;
100     Logistics  Wichita    666
200     Finance    Boise      555
300     Marketing  Pierre     666
400    HR              Paris     777
;
run;


proc sql;
select a.dept_no,c.dept_name,a.id,a.name,a.hire_date format=date9.
from emp a
inner join
(select dept_no,max(hire_date) as rec_date format=date9.
from emp group by 1) b
on a.dept_no=b.dept_no
inner join dept c
on a.dept_no=c.dept_no
where a.hire_date=b.rec_date
order by 5 desc;
quit;
                         dept_no  Dept_name        id  name      hire_date
                      ƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒ
                           300  Marketin        999  Lopez     12DEC2105
                           100  Logistic        666  williams  30JAN2104
                           200  Finance         555  Kearny    08FEB2102
                           400  HR              990  McCabe    10DEC2015

SQL查询_无法找到最近雇用的员工是每个部门

6 个答案: