Oracle : Query to get the Last Friday of the week if I give any date

Question

If I give a date let's say '13-Mar-2019' my query needs to retrieve the value '15-Mar-2019'. Which is the last Friday of the week.

Answer 1

Trancate the date to the ISO week, which gets you the week's Monday (as an ISO week starts with Monday). Then add four days:

select trunc(date '2019-03-13', 'iw') + 4 from dual;