Как сгенерировать периоды списка каждые 30 дней с начала до сегодняшнего дня

Question

Я работаю в компании, которая просит меня создать список периодов за каждые 30 дней с момента запуска элемента до настоящего времени. Образец: Пункт «A» имеет дату начала 01/DEC/2016, а позиция «B» начинается с даты 05/Feb/2016. Сегодня 07/FEB/2017.

Вывод должен нравится:

**ITEM  | START  | END  | PERIOD_NO** 
---------------------------------------------- 
A   |01/12/2016 |30/12/2016 |0 
A   |31/12/2016 |29/01/2017 |1 
A   |30/01/2017 |28/02/2017 |2 
B   |05/07/2016 |03/08/2016 |0 
B   |04/08/2016 |02/09/2016 |1 
B   |03/09/2016 |02/10/2016 |2 
B   |03/10/2016 |01/11/2016 |3 
B   |02/11/2016 |01/12/2016 |4 
B   |02/12/2016 |31/12/2016 |5 
B   |01/01/2017 |30/01/2017 |6 
B   |31/01/2017 |01/03/2017 |7 

Вот мой код:

select 
      ITEM 
      , trunc(Start_Date+(level*30)-30) AS BEGIN 
      , CASE WHEN (Level-1) = 0 THEN trunc(Start_Date+(level*30) - 1) ELSE trunc(Start_Date+(level*30) -1) END AS END 
      , Level-1 AS Period   
    from 
    (
     Select 'A' ITEM 
       ,To_Date('05/07/2016', 'dd/MM/YYYY') Start_Date 
       , TRUNC(sysdate) END_Date        
       From Dual 
     /* UNION ALL 
     Select 
       'B' ITEM 
       , To_Date('01/02/2014', 'dd/MM/YYYY') Start_Date 
       , TRUNC(sysdate) END_Date        
       From Dual*/ 
    ) t 
    connect by level < (((END_DATE - START_DATE)/30) + 1) 

Как это работает только для только одного элемента, я хотел бы обратиться к Вам за советом, как исправить его работает для 2 или более предметов.

Заранее спасибо.

Answer 1

with t (item,start_date) as 
     (
         select 'A',date '2016-12-01' from dual 
      union all select 'B',date '2016-02-05' from dual 
     ) 

select   t.item 
       ,start_date + 30*(level-1)  as start_date 
       ,start_date + 30*level - 1  as end_date 
       ,level - 1      as period_no 

from   t   

connect by  item = prior item 
      and level <= 1 + (sysdate - start_date)/30 
      and prior sys_guid() is not null 

---

+------+---------------------+---------------------+-----------+ 
| ITEM | START_DATE   | END_DATE   | PERIOD_NO | 
+------+---------------------+---------------------+-----------+ 
| A | 2016-12-01 00:00:00 | 2016-12-30 00:00:00 | 0   | 
+------+---------------------+---------------------+-----------+ 
| A | 2016-12-31 00:00:00 | 2017-01-29 00:00:00 | 1   | 
+------+---------------------+---------------------+-----------+ 
| A | 2017-01-30 00:00:00 | 2017-02-28 00:00:00 | 2   | 
+------+---------------------+---------------------+-----------+ 
| B | 2016-02-05 00:00:00 | 2016-03-05 00:00:00 | 0   | 
+------+---------------------+---------------------+-----------+ 
| B | 2016-03-06 00:00:00 | 2016-04-04 00:00:00 | 1   | 
+------+---------------------+---------------------+-----------+ 
| B | 2016-04-05 00:00:00 | 2016-05-04 00:00:00 | 2   | 
+------+---------------------+---------------------+-----------+ 
| B | 2016-05-05 00:00:00 | 2016-06-03 00:00:00 | 3   | 
+------+---------------------+---------------------+-----------+ 
| B | 2016-06-04 00:00:00 | 2016-07-03 00:00:00 | 4   | 
+------+---------------------+---------------------+-----------+ 
| B | 2016-07-04 00:00:00 | 2016-08-02 00:00:00 | 5   | 
+------+---------------------+---------------------+-----------+ 
| B | 2016-08-03 00:00:00 | 2016-09-01 00:00:00 | 6   | 
+------+---------------------+---------------------+-----------+ 
| B | 2016-09-02 00:00:00 | 2016-10-01 00:00:00 | 7   | 
+------+---------------------+---------------------+-----------+ 
| B | 2016-10-02 00:00:00 | 2016-10-31 00:00:00 | 8   | 
+------+---------------------+---------------------+-----------+ 
| B | 2016-11-01 00:00:00 | 2016-11-30 00:00:00 | 9   | 
+------+---------------------+---------------------+-----------+ 
| B | 2016-12-01 00:00:00 | 2016-12-30 00:00:00 | 10  | 
+------+---------------------+---------------------+-----------+ 
| B | 2016-12-31 00:00:00 | 2017-01-29 00:00:00 | 11  | 
+------+---------------------+---------------------+-----------+ 
| B | 2017-01-30 00:00:00 | 2017-02-28 00:00:00 | 12  | 
+------+---------------------+---------------------+-----------+ 

Answer 2

Числа КТР, немного математики и саз

With numbers (NN) as 
(
select 0 as NN 
from dual 
union all 
select NN+1 
from numbers 
where NN < 100 
) 
, CTE as 
(
select item, 
     StartDate+(NN*30) as StartList, 
     row_number() over(partition by ITEM order by StartDate+(NN*30)) as PeriodNo 
from Numbers 
cross join MyTable 
where StartDate+(NN*30) < sysdate 
) 
select Item, 
     StartList, 
     case 
     when StartList +29 > sysdate then sysdate 
     else StartList +29 > sysdate 
     end as enddate, 
     PeriodNo 
from CTE 

Answer 3

В Oracle 11g и ниже, вы можете использовать вложенные таблицы для достижения этой цели:

with t (dt) as (
    select to_date('01/12/2016','dd/mm/yyyy') from dual union all 
    select to_date('05/07/2016','dd/mm/yyyy') from dual 
) 
select 
    t.dt + (x.column_value - 1) * 30 start_date, 
    t.dt + x.column_value * 30 - 1 end_date, 
    x.column_value - 1 period_id 
from t cross join table(cast(
    multiset(
     select level 
     from dual 
     connect by t.dt + 30 * (level - 1) <= sysdate 
    ) as sys.odcinumberlist 
)) x; 

Если вы используете Oracle 12c + , вы можете использовать OUTER APPLY что значительно упрощает синтаксис:

with t (dt) as (
    select to_date('01/12/2016','dd/mm/yyyy') from dual union all 
    select to_date('05/07/2016','dd/mm/yyyy') from dual 
) 
select 
    t.dt + (x.n - 1) * 30 start_date, 
    t.dt + x.n * 30 - 1 end_date, 
    x.n - 1 period_id 
from t outer apply (
    select level n 
    from dual 
    connect by t.dt + 30 * (level - 1) <= sysdate 
) x; 

Оба выше д uery производит:

+------------+-----------+-----------+ 
| START_DATE | END_DATE | PERIOD_ID | 
+------------+-----------+-----------+ 
| 01-DEC-16 | 30-DEC-16 | 0   | 
+------------+-----------+-----------+ 
| 31-DEC-16 | 29-JAN-17 | 1   | 
+------------+-----------+-----------+ 
| 30-JAN-17 | 28-FEB-17 | 2   | 
+------------+-----------+-----------+ 
| 05-JUL-16 | 03-AUG-16 | 0   | 
+------------+-----------+-----------+ 
| 04-AUG-16 | 02-SEP-16 | 1   | 
+------------+-----------+-----------+ 
| 03-SEP-16 | 02-OCT-16 | 2   | 
+------------+-----------+-----------+ 
| 03-OCT-16 | 01-NOV-16 | 3   | 
+------------+-----------+-----------+ 
| 02-NOV-16 | 01-DEC-16 | 4   | 
+------------+-----------+-----------+ 
| 02-DEC-16 | 31-DEC-16 | 5   | 
+------------+-----------+-----------+ 
| 01-JAN-17 | 30-JAN-17 | 6   | 
+------------+-----------+-----------+ 
| 31-JAN-17 | 01-MAR-17 | 7   | 
+------------+-----------+-----------+ 

Ниже запрос выдает строки для каждой строки вашей таблицы с помощью иерархического CONNECT BY:

select level n 
    from dual 
    connect by t.dt + 30 * (level - 1) <= sysdate 

И КТР ниже построить тестовую таблицу:

with t (dt) as (
    select to_date('01/12/2016','dd/mm/yyyy') from dual union all 
    select to_date('05/07/2016','dd/mm/yyyy') from dual 
)