(Oracle 11g DB) Calculate Number of buisiness days between current time and a date while excluding holidays in a view - oracle

Question

So I have this working SQL script that take a date and returns the age from current time to the given date excluding dates defined in a table called exclude dates
SELECT
COUNT(*)
FROM
(
SELECT
ROWNUM rnum
FROM
all_objects
WHERE
ROWNUM <= CAST(current_timestamp AS DATE) - to_date('&2') + 1
)
WHERE
to_char(to_date('&2') + rnum - 1, 'DY') NOT IN ( 'SAT', 'SUN' )
AND NOT EXISTS (
SELECT
NULL
FROM
exclude_dates
WHERE
no_work = trunc(to_date('&2') + rnum - 1)
);
I have a table called
TICKETS
that contains columns named
ID, UPDATED_AT
I want to create a view that uses the above script to return
ID, AGE
where age is the output of the script above.

Answer 1

You code has a few weaknesses.
There is no need for CAST(current_timestamp AS DATE).
If you need the current DATE then simply use TRUNC(SYSDATE)
You don't need to select from all_objects. Better use hierarchical query
SELECT LEVEL as rnum FROM dual CONNECT BY LEVEL <= ...
Using to_date('&2') without a format is usually bad. Either your input value is a string, then you should include the format, e.g. to_date('&2', 'YYYY-MM-DD') or your input value is a DATE, then simply use &2 - never use TO_DATE() on a value which is already a DATE!
Final query could be this one - assuming input parameter is a DATE value:
WITH t AS (
SELECT LEVEL as d
FROM dual
CONNECT BY LEVEL <= TRUNC(SYSDATE) - the_day)
SELECT COUNT(*) AS buisiness_days
FROM t
WHERE TO_CHAR(the_day + d - 1, 'DY', 'NLS_DATE_LANGUAGE = american') NOT IN ('SAT', 'SUN')
AND NOT EXISTS (
SELECT 'x'
FROM exclude_dates
WHERE no_work = TRUNC(the_day + d - 1)
)
However, for me it is not clear how you want to provide this as a view! You would need to create a separate view for each input date, or at least create a new view every day.
I would suggest to create a function:
CREATE OR REPLACE FUNCTION buisiness_days(the_date IN DATE) RETURN INTEGER AS
ret INTEGER;
BEGIN
WITH t AS (
SELECT LEVEL as d
FROM dual
CONNECT BY LEVEL <= TRUNC(SYSDATE) - the_date)
SELECT COUNT(*) AS buisiness_days
INTO ret
FROM t
WHERE TO_CHAR(the_date + d - 1, 'DY', 'NLS_DATE_LANGUAGE = american') NOT IN ('SAT', 'SUN')
AND NOT EXISTS (
SELECT 'x'
FROM exclude_dates
WHERE no_work = TRUNC(the_date + d - 1)
);
RETURN ret;
END;

Answer 2

The function will return a list of dates between the date range you provide so the dates don't have to be stored in a table.
CREATE OR REPLACE TYPE nt_date IS TABLE OF DATE;
/
CREATE OR REPLACE FUNCTION generate_dates_pipelined(
p_from IN DATE,
p_to IN DATE
)
RETURN nt_date PIPELINED DETERMINISTIC
IS
v_start DATE := TRUNC(LEAST(p_from, p_to));
v_end DATE := TRUNC(GREATEST(p_from, p_to));
BEGIN
LOOP
PIPE ROW (v_start);
EXIT WHEN v_start >= v_end;
v_start := v_start + INTERVAL '1' DAY;
END LOOP;
RETURN;
END generate_dates_pipelined;
/
To exclude holidays you need to know what dates they fall on so there needs to be a holiday table.
create table holidays(
holiday_date DATE not null,
holiday_name VARCHAR2(20),
constraint holidays_pk primary key (holiday_date),
constraint is_midnight check ( holiday_date = trunc ( holiday_date ) )
);
INSERT into holidays (HOLIDAY_DATE,HOLIDAY_NAME)
WITH dts as (
select to_date('25-NOV-2021 00:00:00','DD-MON-YYYY HH24:MI:SS'), 'Thanksgiving 2021' from dual union all
select to_date('29-NOV-2021 00:00:00','DD-MON-YYYY HH24:MI:SS'), 'Hanukkah 2021' from dual
)
SELECT * from dts;
This query will provide the count of days between the range, number of working days and number of holidays in the range.
SELECT COUNT (*) AS total_days
, COUNT ( CASE
WHEN h.holiday_date IS NULL
AND d.column_value - TRUNC (d.column_value, 'IW') < 5
THEN 'Business Day'
END
) AS business_days
, COUNT (h.holiday_date) AS holidays
FROM generate_dates_pipelined (DATE '2021-11-01', DATE '2021-11-30') d
LEFT JOIN holidays h ON h.holiday_date = d.column_value;
This query will provide a list of dates excluding sat, sun and holidays that fall between the range.
SELECT
COLUMN_VALUE
FROM
TABLE(generate_dates_pipelined(DATE '2021-11-01',
DATE '2021-11-30')) c
where
to_char(COLUMN_VALUE, 'DY') NOT IN ('SAT', 'SUN')
AND NOT EXISTS (
SELECT 1
FROM holidays h
WHERE c.COLUMN_VALUE = h.holiday_date
);

Answer 3

You don't need a function or to use a row generator function and can calculate the number of business days:
CREATE VIEW business_day_ages (ID, AGE) AS
SELECT id,
( TRUNC( SYSDATE, 'IW' ) - TRUNC( updated_at, 'IW' ) ) * 5 / 7
-- Number of full weeks.
+ LEAST( SYSDATE - TRUNC( SYSDATE, 'IW' ), 5 )
-- Add part weeks at the end.
- LEAST( updated_at - TRUNC( updated_at, 'IW' ), 5 )
-- Subtract part weeks at the start.
- COALESCE(
( SELECT SUM(
LEAST(no_work + INTERVAL '1' DAY, SYSDATE)
- GREATEST(no_work, updated_at)
)
FROM exclude_dates
WHERE no_work BETWEEN TRUNC(updated_at) AND SYSDATE
),
0
)
-- Subtract the holiday days.
FROM tickets;
Or, if you are not calculating using part days then you can simplify it to:
CREATE OR REPLACE VIEW business_day_ages (ID, AGE) AS
SELECT id,
( TRUNC( SYSDATE, 'IW' ) - TRUNC( updated_at, 'IW' ) ) * 5 / 7
-- Number of full weeks.
+ LEAST( TRUNC(SYSDATE) - TRUNC( SYSDATE, 'IW' ), 5 )
-- Add part weeks at the end.
- LEAST( updated_at - TRUNC( updated_at, 'IW' ), 5 )
-- Subtract part weeks at the start.
- COALESCE(
( SELECT 1
FROM exclude_dates
WHERE no_work BETWEEN TRUNC(updated_at) AND TRUNC(SYSDATE)
),
0
)
-- Subtract the holiday days.
FROM tickets;
db<>fiddle here