Return time between two dates except weekends - sql

Question

I need to return the time between two dates in Oracle except the time during the weekends, I could return the minute. But when I set a weekend date, I receive a null result instead of the remaining time in workweek.
First, we need to create a function:
CREATE OR REPLACE FUNCTION get_bus_minutes_between (start_dt DATE, end_dt DATE)
RETURN NUMBER
IS
v_return NUMBER;
BEGIN
select sum(greatest(end_dt - start_dt,0)) * 24 * 60 work_minutes
into v_return
from dual
where trunc(start_dt) - trunc(start_dt,'iw') < 5; -- exclude weekends
RETURN v_return;
END;
Case 1 - Return the minutes in the workweek - Ok
Starting and ending in the workweek.
SELECT
"GET_BUS_MINUTES_BETWEEN"(TO_DATE('14-09-2020 06:00:00', 'dd-mm-yyyy hh24:mi:ss'),
TO_DATE('14-09-2020 10:00:00', 'dd-mm-yyyy hh24:mi:ss')) "WORK_MINUTES"
FROM
"SYS"."DUAL";
Case 2 - Return the remaining minutes in the workweek - Fail
Starting at the weekend and ending in workweek.
SELECT
"GET_BUS_MINUTES_BETWEEN"(TO_DATE('13-09-2020 06:00:00', 'dd-mm-yyyy hh24:mi:ss'),
TO_DATE('14-09-2020 10:00:00', 'dd-mm-yyyy hh24:mi:ss')) "WORK_MINUTES"
FROM
"SYS"."DUAL";
13-09-2020 is Sunday, therefore I was expected the return as 600 minutes related the Monday.
In these possibilities, we can start at the workweek and end at weekend.

Answer 1

You don't need to use SQL or a row generator and can do it with a simple calculation using only PL/SQL. Adapted from my answers here and here.
CREATE OR REPLACE FUNCTION get_bus_minutes_between (start_dt DATE, end_dt DATE)
RETURN NUMBER
IS
p_start_date DATE;
p_end_date DATE;
p_working_days NUMBER;
BEGIN
IF start_dt IS NULL OR end_dt IS NULL THEN
RETURN NUll;
END IF;
-- Enforce that the values are earliest start date to latest end date.
p_start_date := LEAST( start_dt, end_dt );
p_end_date := GREATEST( start_dt, end_dt );
-- Calculate the number of days from the beginning of the ISO week containing
-- the start date and the beginning of the ISO week containing the end date
-- and then multiply this by 5/7 to get the number of full business days.
--
-- Then add on the extra days from the beginining of the ISO week containing
-- the end date and the end date and subtract the extra days from the
-- beginning of the ISO week containing the start date to the start date.
p_working_days := ( TRUNC( p_end_date, 'IW' ) - TRUNC( p_start_date, 'IW' ) ) * 5 / 7
+ LEAST( p_end_date - TRUNC( p_end_date, 'IW' ), 5 )
- LEAST( p_start_date - TRUNC( p_start_date, 'IW' ), 5 );
-- If the start date and end date are reversed then return a negative value.
IF start_dt > end_dt THEN
RETURN -ROUND( p_working_days * 24 * 60, 3 );
ELSE
RETURN +ROUND( p_working_days * 24 * 60, 3 );
END IF;
END;
/
Then:
SELECT GET_BUS_MINUTES_BETWEEN(
DATE '2020-09-14' + INTERVAL '6' HOUR,
DATE '2020-09-14' + INTERVAL '10' HOUR
) AS minutes_between
FROM DUAL;
Outputs:
| MINUTES_BETWEEN |
| --------------: |
| 240 |
and:
SELECT GET_BUS_MINUTES_BETWEEN(
DATE '2020-09-13' + INTERVAL '6' HOUR,
DATE '2020-09-14' + INTERVAL '10' HOUR
) AS minutes_between
FROM DUAL;
outputs:
| MINUTES_BETWEEN |
| --------------: |
| 600 |
db<>fiddle here

Answer 2

If the intervals are not too big, one method uses a brute force approach to generate all minutes in the range, then exclude week-ends:
with cte(dt, end_dt) as (
select start_dt, end_dt from dual
union all
select dt + 1 / 24 / 60, end_dt from cte where dt < end_dt
)
select count(*) work_minutes
from cte
where trunc(dt) - trunc(dt,'iw') < 5
If the intervals are not too big, one method uses a brute force approach to generate all minutes in the range, then exclude week-ends:
with cte(dt, end_dt) as (
select start_dt, end_dt from dual
union all
select dt + 1 / 24 / 60, end_dt from cte where dt < end_dt
)
select count(*) work_minutes
from cte
where to_char(dt, 'IW') <= 5
If you have large intervals, we can reduce the number of iterations by pre-generating minutes / hours series:
with
params (start_dt, end_dt) as (
select start_dt, end_dt from dual
)
minutes (mi) as (
select 0 from dual
union all select mi + 1 from minutes where mi < 59
),
hours (hr) as (
select 0 from dual
union all select hr + 1 from hours where hr < 23
)
select count(*) work_minutes
from params p
cross join minutes m
cross join hours h
where
p.start_dt + h.hr / 24 + m.mi / 24 / 60 <= end_dt
and trunc(p.start_dt + h.hr / 24 + m.mi / 24 / 60) - trunc(p.start_dt + h.hr / 24 + m.mi / 24 / 60,'iw') < 5