Resetting a date value if it falls on weekend - sql

Question

I am writing a procedure and using dynamic cursor and SQL query which I am passing as string in V_SQL variable. Query is as following:
In the where condition, I'm passing date but the condition is that if it's month end and it falls on Friday, Saturday or sunday then reset it to Thursday. for instance, 30th June will be sunday so value passed to day_of_month in SQL query should be 27 i.e. day no from Thursday date.
Could you please help me whether writing separate function will be good and what code should I put for better performance and desired result.
V_SQL := 'SELECT B.FIN_ELEM, A.ORG_UNIT_ID, A.GL_ACCOUNT_ID, B.CMN_COA_ID, B.PROD1, B.PROD2, B.PROD3, '||
'A.AS_OF_DATE, SUM(CURRENT_BAL) AS CB_SUM, SUM(AVG_BAL) AS AB_SUM, B.FLAG1 FROM DAILYGL A, AL_LOOKUP B '||
'WHERE A.GL_ACCOUNT_ID = B.GL_ACCT ***AND DAY_OF_MONTH = '|| TO_DO_FUNCTION(V_RUN_DATE)***
' AND ROWNUM <=15 GROUP BY B.FIN_ELEM, A.ORG_UNIT_ID, A.GL_ACCOUNT_ID,B.CMN_COA_ID, B.PROD1, B.PROD2, B.PROD3';
DAY_OF_MONTH = '|| TO_DO_FUNCTION(V_RUN_DATE)
Desired result will be passed Thursday day number if last business day is in fri, sat or sunday.

Answer 1

You don't really need a function, you can achieve this with a case expression, something like:
AND DAY_OF_MONTH = case
when last_day(v_run_date) - v_run_date <= 3
and to_char(v_run_date, 'Dy', 'NLS_DATE_LANGUAGE=ENGLISH') in ('Fri', 'Sat', 'Sun')
and to_char(last_day(v_run_date), 'Dy', 'NLS_DATE_LANGUAGE=ENGLISH') in ('Fri', 'Sat', 'Sun')
then next_day(trunc(v_run_date, 'IW'), 'THURSDAY')
else v_run_date
end
That is, if v_run_date is within three days of the last day of the month, and v_run_date is a Friday, Saturday or Sunday, and the last day of the month is a Friday, Saturday or Sunday, then use the date of that week's Thursday.
Demo with dates generated for all of this year:
with cte (v_run_date) as (
select date '2018-12-31' + level
from dual
connect by level <= 365
)
select v_run_date,
to_char(v_run_date, 'Dy', 'NLS_DATE_LANGUAGE=ENGLISH') as dy,
case
when last_day(v_run_date) - v_run_date <= 3
and to_char(v_run_date, 'Dy', 'NLS_DATE_LANGUAGE=ENGLISH') in ('Fri', 'Sat', 'Sun')
and to_char(last_day(v_run_date), 'Dy', 'NLS_DATE_LANGUAGE=ENGLISH') in ('Fri', 'Sat', 'Sun')
then next_day(trunc(v_run_date, 'IW'), 'THURSDAY')
else v_run_date
end as adjusted_date
from cte;
V_RUN_DATE DY ADJUSTED_D
---------- ------------ ----------
2019-01-01 Tue 2019-01-01
2019-01-02 Wed 2019-01-02
...
2019-01-30 Wed 2019-01-30
2019-01-31 Thu 2019-01-31
2019-02-01 Fri 2019-02-01
2019-02-02 Sat 2019-02-02
...
2019-03-26 Tue 2019-03-26
2019-03-27 Wed 2019-03-27
2019-03-28 Thu 2019-03-28
2019-03-29 Fri 2019-03-28
2019-03-30 Sat 2019-03-28
2019-03-31 Sun 2019-03-28
2019-04-01 Mon 2019-04-01
...
2019-04-30 Tue 2019-04-30
2019-05-01 Wed 2019-05-01
...
2019-05-28 Tue 2019-05-28
2019-05-29 Wed 2019-05-29
2019-05-30 Thu 2019-05-30
2019-05-31 Fri 2019-05-30
2019-06-01 Sat 2019-06-01
2019-06-02 Sun 2019-06-02
...
2019-06-26 Wed 2019-06-26
2019-06-27 Thu 2019-06-27
2019-06-28 Fri 2019-06-27
2019-06-29 Sat 2019-06-27
2019-06-30 Sun 2019-06-27
2019-07-01 Mon 2019-07-01
...
2019-07-31 Wed 2019-07-31
2019-08-01 Thu 2019-08-01
...
2019-08-28 Wed 2019-08-28
2019-08-29 Thu 2019-08-29
2019-08-30 Fri 2019-08-29
2019-08-31 Sat 2019-08-29
2019-09-01 Sun 2019-09-01
...
2019-11-27 Wed 2019-11-27
2019-11-28 Thu 2019-11-28
2019-11-29 Fri 2019-11-28
2019-11-30 Sat 2019-11-28
2019-12-01 Sun 2019-12-01
...
db<>fiddle
As mentioned in a comment, your code doesn't appear to need to be dynamic; you can use static SQL for what you've shown, e.g.:
SELECT *
-- into ...
FROM (
SELECT B.FIN_ELEM, A.ORG_UNIT_ID, A.GL_ACCOUNT_ID,
B.CMN_COA_ID, B.PROD1, B.PROD2, B.PROD3, A.AS_OF_DATE,
SUM(CURRENT_BAL) AS CB_SUM, SUM(AVG_BAL) AS AB_SUM, B.FLAG1
FROM DAILYGL A
JOIN AL_LOOKUP B ON B.GL_ACCT = A.GL_ACCOUNT_ID
WHERE DAY_OF_MONTH = case
when last_day(v_run_date) - v_run_date <= 3
and to_char(v_run_date, 'Dy', 'NLS_DATE_LANGUAGE=ENGLISH') in ('Fri', 'Sat', 'Sun')
and to_char(last_day(v_run_date), 'Dy', 'NLS_DATE_LANGUAGE=ENGLISH') in ('Fri', 'Sat', 'Sun')
then next_day(trunc(v_run_date, 'IW'), 'THURSDAY')
else v_run_date
end
GROUP BY B.FIN_ELEM, A.ORG_UNIT_ID, A.GL_ACCOUNT_ID,B.CMN_COA_ID, B.PROD1, B.PROD2, B.PROD3
-- order by something...
)
WHERE ROWNUM <= 15;
I've also switched to ANSI joins but more importantly moved the main query into an inline view, and then applied the rownum filter to that; which will make no difference unless/until you add an order-by clause inside that inline view. Without it this, and your original, will get an indeterminate (not quite random, but similar effect) set of 15 rows back. If you order the inner query then you'll always get the first 15 rows according to your ordering criteria. From 12c you can use a row limiting clause instead of the subquery/rownum filter, but this approach will work in earlier versions.
Obviously you still need to either select that into variables or use it as a cursor query - whatever you had planned to do dynamically.

Answer 2

I hope this will solve your problem
V_RUN_DATE - (case when V_RUN_DATE > LAST_DAY (V_RUN_DATE)- 3 then V_RUN_DATE else
(case TO_CHAR(date V_RUN_DATE, 'DY') when 'FRI' then 1 when 'SAT' then 2 when 'SUN' then 3 else 0 end) end)