Oracle 18c

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select * from V$VERSION;


BANNER
BANNER_FULL
BANNER_LEGACY
CON_ID


Oracle Database 18c Express Edition Release 18.0.0.0.0 - Production
Oracle Database 18c Express Edition Release 18.0.0.0.0 - Production
Version 18.4.0.0.0
Oracle Database 18c Express Edition Release 18.0.0.0.0 - Production
0


create table employees as 
with employees (id, dept, salary, begin_date, end_date, man_id) as (
    select 1, 22, 3500.86, to_date ('01.07.19', 'dd.mm.yy'), to_date ('01.05.20', 'dd.mm.yy'), 1 from dual union all
    select 1, 24, 2000.86, to_date ('01.06.19', 'dd.mm.yy'), to_date ('01.05.20', 'dd.mm.yy'), 2 from dual union all
    select 2, 23, 3500.86, to_date ('01.06.19', 'dd.mm.yy'), to_date ('01.05.20', 'dd.mm.yy'), 2 from dual union all
    select 3, 24, 3500.86, to_date ('01.06.19', 'dd.mm.yy'), to_date ('01.05.20', 'dd.mm.yy'), 3 from dual union all
    select 4, 22, 2000.86, to_date ('01.06.19', 'dd.mm.yy'), to_date ('01.05.20', 'dd.mm.yy'), 3 from dual union all
    select 7, 21, 3500.86, to_date ('01.05.19', 'dd.mm.yy'), to_date ('01.05.20', 'dd.mm.yy'), 1 from dual)
select * from employees
/
6 rows affected

-- с внутренним соединением
select dept, 
    coalesce ("'012019'", 0) "012019", coalesce ("'022019'", 0) "022019",
    coalesce ("'032019'", 0) "032019", coalesce ("'042019'", 0) "042019",
    coalesce ("'052019'", 0) "052019", coalesce ("'062019'", 0) "062019",
    coalesce ("'072019'", 0) "072019", coalesce ("'082019'", 0) "082019",
    coalesce ("'092019'", 0) "092019", coalesce ("'102019'", 0) "102019",
    coalesce ("'112019'", 0) "112019", coalesce ("'122019'", 0) "122019"
from (
    select dept, to_char (m.fday, 'mmyyyy') mmyyyy, count (id) emps  
    from employees e 
    join (
        select add_months (date'2019-01-01', level-1) fday 
        from dual connect by level <= 12) m on (e.begin_date <= m.fday and m.fday < e.end_date) 
    group by dept, to_char (m.fday, 'mmyyyy'))
pivot (sum (emps) for mmyyyy in (
    '012019','022019','032019','042019','052019','062019',
    '072019','082019','092019','102019','112019','122019'))


DEPT
012019
022019
032019
042019
052019
062019
072019
082019
092019
102019
112019
122019


22
0
0
0
0
0
1
2
2
2
2
2
2

21
0
0
0
0
1
1
1
1
1
1
1
1

23
0
0
0
0
0
1
1
1
1
1
1
1

24
0
0
0
0
0
2
2
2
2
2
2
2


-- с кросс соединением
select * from (
    select 
        dept, to_char (m.fday, 'mmyyyy') as mmyyyy, 
        count (case when e.begin_date <= m.fday and m.fday < e.end_date then 1 end) as emps  
    from employees e 
    cross join (
        select add_months (date'2019-01-01', level-1) fday 
        from dual connect by level <= 12) m 
    group by dept, to_char (m.fday, 'mmyyyy'))
pivot (sum (emps) for mmyyyy in (
    '012019' as "012019",'022019' as "022019",'032019' as "032019",
    '042019' as "042019",'052019' as "052019",'062019' as "062019",
    '072019' as "072019",'082019' as "082019",'092019' as "092019",
    '102019' as "102019",'112019' as "112019",'122019' as "122019"))
/


DEPT
012019
022019
032019
042019
052019
062019
072019
082019
092019
102019
112019
122019


22
0
0
0
0
0
1
2
2
2
2
2
2

21
0
0
0
0
1
1
1
1
1
1
1
1

23
0
0
0
0
0
1
1
1
1
1
1
1

24
0
0
0
0
0
2
2
2
2
2
2
2