如何根据日期显示当前信息

Question

我的 sql 脚本遇到问题，该脚本要求我显示公司、员工编号、姓氏、名字、当前工作和当前工资。我知道要达到“当前”的某些内容意味着涉及日期。 我想要实现的是显示该员工当前的工作和工资。

>>这些是使用的表格和视图<<

注意：表格内的信息并非真实信息。我只是改变它，这样你仍然可以得到我指出的内容。

emp表

+-------+----------+-----------+
| empno | lastname | firstname |
+-------+----------+-----------+
|  111  |  james   |  lebron   |
|  222  |  bryant  |   kobe    |
|  333  |  jordan  |  michael  |
|  444  |  curry   |  stephen  |
+-------+----------+-----------+

部门工作视图

+------------+--------+-----------+------------+------------+
|   company  |  empno |  effdate  |     job    |   salary   |
+------------+--------+-----------+------------+------------+
|   lakers   |  111   |  04/16/15 |  assistant |  1500.00   |
|   lakers   |  111   |  02/02/16 |    coach   |  4000.00   |
|   lakers   |  222   |  07/22/17 |   analyst  |  3000.00   |
|    bulls   |  333   |  04/12/17 |  secretary |  5000.00   |
|    bulls   |  333   |  07/28/18 |   manager  |  5000.00   |
|  warriors  |  444   |  10/04/19 |    chef    |  2000.00   |
+------------+--------+-----------+------------+------------+

我所做的是，我使用 Max() 函数来获取有效日期（effdate），以可能获得最新的工作和薪水。但即使在那之后，它仍然显示他过去的工作和薪水。我需要显示当前的工作和薪水。

SELECT z.company, em.empno, em.lastname, em.firstname, z.job, z.salary
FROM emp em
JOIN ( SELECT dj.company, dj.empno, dj.effdate, dj.job, dj.salary FROM dept_job dj
JOIN (SELECT company, empno, MAX(effdate) AS maxefffdate FROM dept_job
GROUP BY company, empno) pe  ON dj.empno = pc.empno AND dj.effdate = pe.maxeffdate) z
ON em.empno = z.empno
ORDER BY company, empno;

错误结果：

+------------+--------+----------+-----------+------------+------------+
|   company  |  empno | lastname | firstname |     job    |   salary   |
+------------+--------+----------+-----------+------------+------------+
|   lakers   |  111   |  james   |  lebron   |  assistant |  1500.00   |
|   lakers   |  111   |  james   |  lebron   |    coach   |  4000.00   |
|   lakers   |  222   |  bryant  |   kobe    |   analyst  |  3000.00   |
|    bulls   |  333   |  jordan  |  michael  |  secretary |  5000.00   |
|    bulls   |  333   |  jordan  |  michael  |   manager  |  5000.00   |
|  warriors  |  444   |  curry   |  stephen  |    chef    |  2000.00   |
+------------+--------+----------+-----------+------------+------------+

我想要达到的目标

+------------+--------+----------+-----------+------------+------------+
|   company  |  empno | lastname | firstname |     job    |   salary   |
+------------+--------+----------+-----------+------------+------------+
|   lakers   |  111   |  james   |  lebron   |    coach   |  4000.00   |
|   lakers   |  222   |  bryant  |   kobe    |   analyst  |  3000.00   |
|    bulls   |  333   |  jordan  |  michael  |   manager  |  5000.00   |
|  warriors  |  444   |  curry   |  stephen  |    chef    |  2000.00   |
+------------+--------+----------+-----------+------------+------------+

Answer 1

您可以从下面的查询中获得所需的输出：

SELECT dj.company
    ,em.empno
    ,em.lastname
    ,em.firstname
    ,dj.job
    ,dj.salary
FROM emp em
JOIN dept_job dj ON em.empno = dj.empno
JOIN (
    SELECT empno
        ,MAX(effdate) AS maxefffdate
    FROM dept_job
    GROUP BY empno
    ) z ON dj.empno = z.empno
    AND dj.effdate = z.maxefffdate
ORDER BY company
    ,empno;

Answer 2

您可以将 OVER 与 PARTION BY 一起使用，并执行以下操作：

选择 z.company、em.empno、em.lastname、em.firstname、z.job、z.salary 来自 emp em JOIN ( 选择 dj.company, dj.empno, MAX(dj.effdate) OVER ( 按 dj.company、dj.empno、dj.job、dj.salary 分区 ) AS maxeffdate、dj.job、dj.salary 来自 dept_job dj ) z ON em.empno = z.empno 按公司、员工订购；