ORACLE SQL: Create new row on the basis of date range - sql

Question

For example, I am having a table name test_cross_months and the data is as below :
id
start_date
end_date
44
2020-01-04
2020-01-04
44
2020-01-30
2020-02-10
44
2020-02-27
2020-03-03
Expected result:
id
start_date
end_date
44
2020-01-04
2020-01-04
44
2020-01-30
2020-01-31
44
2020-02-01
2020-02-10
44
2020-02-27
2020-02-29
44
2020-03-01
2020-03-03
So for
|44|2020-01-30 |2020-02-10|
there should be two rows that are from 30-Jan-2020 to 31-Jan-2020 and 1-Feb-2020 to 10-Feb-2020
I tried by comparing the end date with the last day for the start_date but facing issues as a new row is not getting created for the end_date range.
Could any please suggest a solution?

Answer 1

You can use a recursive query (which will work regardless of how many months your ranges span):
WITH months ( id, start_date, end_date, final_date ) AS (
SELECT id,
start_date,
LEAST( LAST_DAY( start_date ), end_date ),
end_date
FROM table_name
UNION ALL
SELECT id,
end_date + INTERVAL '1' DAY,
LEAST( ADD_MONTHS( end_date, 1 ), final_date ),
final_date
FROM months
WHERE end_date < final_date
)
SEARCH DEPTH FIRST BY final_date SET dt_order
SELECT id,
start_date,
end_date
FROM months;
Which, for the sample data:
CREATE TABLE table_name (id, start_date, end_date) AS
SELECT 44, DATE '2020-01-04', DATE '2020-01-04' FROM DUAL UNION ALL
SELECT 44, DATE '2020-01-30', DATE '2020-02-10' FROM DUAL UNION ALL
SELECT 44, DATE '2020-02-27', DATE '2020-03-03' FROM DUAL;
Outputs:
ID
START_DATE
END_DATE
44
2020-01-04 00:00:00
2020-01-04 00:00:00
44
2020-01-30 00:00:00
2020-01-31 00:00:00
44
2020-02-01 00:00:00
2020-02-10 00:00:00
44
2020-02-27 00:00:00
2020-02-29 00:00:00
44
2020-03-01 00:00:00
2020-03-03 00:00:00
db<>fiddle here

Answer 2

Using a table of numbers and date arithmetic
-- example of table of numbers
with nmbrs(n) as(
select 0 from dual union all
select 1 from dual union all
select 2 from dual
)
select t.id,
case when n=0 then t.start_date else trunc(t.start_date, 'MM') + NUMTOYMINTERVAL(n, 'MONTH') end s,
case when n=MONTHS_BETWEEN(last_day(t.end_date), last_day(t.start_date)) then t.end_date
else last_day(t.start_date + NUMTOYMINTERVAL(n, 'MONTH')) end e
from test_cross_months t
join nmbrs on nmbrs.n <= MONTHS_BETWEEN(last_day(t.end_date), last_day(t.start_date))
order by t.id, s
db<>fiddle