return the month in between sql - sql

Question

I want to ask is there any way in PL/SQL that I can return the months in between user input.
For example, the user put in
DateStart: 01/2019 and
DateEnd: 05/2019
The query should return
01/2019, 02/2019, 03/2019, 04/2019,05/2019.

Answer 1

You can do this in sql, no pl/sql needed for this.
Convert month/year to a date, 1st of the month.
Then count the months between the first and last argument.
Then select doing a connect by level + 2 (because you're including the boundary values). All put together this gives:
WITH test_data (monthyear_start, monthyear_end) AS
(
SELECT '01/2019', '05/2019' FROM DUAL
),
monthcount(months) AS
(
SELECT MONTHS_BETWEEN(TO_DATE('01/'||monthyear_end,'DD/MM/YYYY'),TO_DATE('01/'||monthyear_start,'DD/MM/YYYY')) FROM test_data
)
SELECT TO_CHAR(ADD_MONTHS(TO_DATE('01/'||monthyear_start,'DD/MM/YYYY'),LEVEL - 1),'MM/YYYY') FROM test_data, monthcount
CONNECT BY LEVEL < months + 2;
01/2019
02/2019
03/2019
04/2019
05/2019

Answer 2

You can firstly use connect by level <= syntax, and then apply listagg() function to concatenate the strings :
with t2 as
(
select distinct to_char( to_date(DateStart,'mm/yyyy') + level - 1 , 'mm/yyyy') as mnt
from t
connect by level <= to_date(DateEnd,'mm/yyyy') - to_date(DateStart,'mm/yyyy') + 1
)
select listagg(mnt,',') within group
(order by to_number(substr(mnt,-4)||substr(mnt,1,2))) as "Months"
from t2
Demo

Answer 3

Similar, but yet different, maybe even simpler than previous suggestions:
SQL> with test (dstart, dend) as
2 (select '01/2019', '05/2019' from dual)
3 select to_char(add_months(to_date(dstart, 'mm/yyyy'), level - 1), 'mm/yyyy') result
4 from test
5 connect by
6 level <= months_between(to_date(dend, 'mm/yyyy'), to_date(dstart, 'mm/yyyy')) + 1;
RESULT
-------
01/2019
02/2019
03/2019
04/2019
05/2019
SQL>

Answer 4

Here is a PL/SQL procedure and some test code.
DECLARE
PROCEDURE p_list_months(start_date IN DATE, end_date IN DATE) AS
v_count INTEGER := 0;
BEGIN
v_count := MONTHS_BETWEEN(end_date, start_date);
FOR i in 0..v_count LOOP
dbms_output.put_line(to_char(add_months(start_date, i),'mm/yyyy'));
END LOOP;
END;
BEGIN
p_list_months(SYSDATE, ADD_MONTHS(SYSDATE, 5));
END;
And a SQL query:
-- start_date 10/2019 end_date 10/2020
SELECT to_char(add_months(TO_DATE('10/2019','mm/yyyy'), LEVEL-1), 'mm/yyyy') dat
FROM dual
CONNECT BY LEVEL <= (MONTHS_BETWEEN( TO_DATE('10/2020','mm/yyyy'),
TO_DATE('10/2019','mm/yyyy'))) + 1;