How to get monthly periods between a date range in Oracle PL/SQL - oracle

Question

I have say, start and end date as "6/11/1996" and "3/1/2002" in "mm/dd/yyyy" format respectively.
I need to get all the monthly periods as given below.
Start Date End Date
6/11/1996 - 6/30/1996
7/01/1996 - 7/31/1996
8/01/1996 - 8/31/1996
.
.
.
Till
2/01/2002 - 2/28/2002
Any help would be highly appreciated.

Answer 1

Assuming the interval is given by way of two bind variables, :from_dt and :to_dt (strings in the indicated format):
with
inputs ( f_dt, t_dt ) as (
select to_date(:from_dt, 'mm/dd/yyyy'), to_date(:to_dt, 'mm/dd/yyyy') from dual
),
ld ( l_day, lvl ) as (
select add_months(last_day(f_dt), level - 1), level
from inputs
connect by level <= months_between(last_day(t_dt), last_day(f_dt)) + 1
)
select case when ld.lvl = 1 then i.f_dt else add_months(ld.l_day, -1) + 1 end
as start_date,
least(i.t_dt, ld.l_day) as end_date
from inputs i cross join ld
;
This assumes that in the original post you did, in fact, mean to have one more interval, from 3/1/2002 to 3/1/2002; and the query deals correctly with the case when the from-date and the to-date are in the same month: if the inputs are 6/11/1996 to 6/21/1996, then the output is exactly that interval.
Added: creating column aliases in the declaration of factored subqueries (in the WITH clause), as I have done, requires Oracle 11.2 or above. For earlier versions, it is necessary to write it a little differently, like so:
with
inputs as (
select to_date(:from_dt, 'mm/dd/yyyy') as f_dt,
to_date(:to_dt , 'mm/dd/yyyy') as t_dt
from dual
),
ld as (
select add_months(last_day(f_dt), level - 1) as l_day, level as lvl
from inputs ...............

Answer 2

You could use connect by query with functions add_months and months_between:
with p as ( select date '1996-06-11' d1, date '2002-03-01' d2 from dual )
select greatest(trunc(add_months(d1, level - 1), 'month'), d1) as d1,
trunc(add_months(d1, level), 'month') - 1 as d2
from p connect by level <= months_between(trunc(d2, 'month'), trunc(d1, 'month'))
The output is exactly as requested.

Answer 3

DECLARE
L_min_date DATE := '11-Jun-1996';
L_max_date DATE := '28-Feb-2002';
L_number_of_months NUMBER := 0;
L_new_date DATE := NULL;
BEGIN
L_number_of_months := MONTHS_BETWEEN(L_max_date, L_min_date);
DBMS_OUTPUT.PUT_LINE('Start_Date End_Date');
FOR i IN 1..L_number_of_months
LOOP
SELECT (ADD_MONTHS(L_min_date, 1) - 1) INTO L_new_date FROM dual;
DBMS_OUTPUT.PUT_LINE(L_min_date || ' - ' || L_new_date);
L_min_date := L_new_date + 1;
END LOOP;
END;
/
Something like above can help.