我如何写雇用同月员工和订单？

Question

Sql，它给出了同月（或同年）按日期分组并按顺序雇用的员工人数。

我尝试编写此代码，但我没有找到相同的雇用和订单。

SELECT hire_date,COUNT(hire_date) 
FROM employees
GROUP BY hire_date;

Answer 1

我是这样理解这个问题的。

示例数据：

SQL> select ename, hiredate from emp order by hiredate;

ENAME      HIREDATE
---------- ----------
SMITH      17_12_1980
ALLEN      20_02_1981
WARD       22_02_1981
JONES      02_04_1981
BLAKE      01_05_1981
CLARK      09_06_1981
TURNER     08_09_1981
MARTIN     28_09_1981
KING       17_11_1981
JAMES      03_12_1981
FORD       03_12_1981
MILLER     23_01_1982
SCOTT      09_12_1982
ADAMS      12_01_1983

14 rows selected.

同月就业：

SQL> select to_char(hiredate, 'mm.yyyy') hire_month,
  2    count(*)
  3  from emp
  4  group by to_char(hiredate, 'mm.yyyy')
  5  order by 1;

HIRE_MO   COUNT(*)
------- ----------
01.1982          1
01.1983          1
02.1981          2
04.1981          1
05.1981          1
06.1981          1
09.1981          2
11.1981          1
12.1980          1
12.1981          2
12.1982          1

11 rows selected.

SQL>

同年入职：

SQL> select extract(year from hiredate) hire_year,
  2    count(*)
  3  from emp
  4  group by extract(year from hiredate)
  5  order by 1;

 HIRE_YEAR   COUNT(*)
---------- ----------
      1980          1
      1981         10
      1982          2
      1983          1

SQL>

我如何写雇用同月员工和订单？

How can i write hired the same month employees and order?

sql

oracle

oracle-apex