PostgreSQL: Adjust columns value based on criteria - sql

Question

Imagine the following data:
student category exam_id adjusted_category
Carl A 44 A
Carl A 55 A
Carl A 88 A
Carl A 1 A
Carl A 2 A
Carl A 3 A
Carl B 1 B
Carl B 2 B
Carl B 3 B
John C 100 C
John C 200 C
John C 300 C
If for the same user, both categories A and B are encountered but specific exam_ids are found (44, 55, 88), I'd like to adjust the category to be A. Otherwise, keep the same category.
The output I'm aiming is:
student adjusted_category
Carl A
Carl C
Code I'm currently attempting to modify:
with my_table (student, category, exam_id)
as (values
('Carl', 'A', 44),
('Carl', 'A', 55),
('Carl', 'A', 88),
('Carl', 'A', 1),
('Carl', 'A', 2),
('Carl', 'A', 3),
('Carl', 'B', 1),
('Carl', 'B', 2),
('Carl', 'B', 3),
('John', 'C', 100),
('John', 'C', 200),
('John', 'C', 300)
)
select *,
case
when category in ('A','B') and exam_id in (44, 55, 88) then 'A'
else category
end as adjusted_category
from my_table
The reason why the code above is not what I'm after is because I end up getting the adjusted category as A only where the exams id_s are 44, 55, or 88. Id's like all of the entries for Carl to have A as the adjusted category.
How can I achieve the desired output?

Answer 1

I may have misinterpreted your requirement. If so, you can change the bool_or() to bool_and(). The bool_or() expression over a window partitioned by student will return true if the student has any one of (44, 55, 88):
with my_table (student, category, exam_id)
as (values
('Carl', 'A', 44),
('Carl', 'A', 55),
('Carl', 'A', 88),
('Carl', 'A', 1),
('Carl', 'A', 2),
('Carl', 'A', 3),
('Carl', 'B', 1),
('Carl', 'B', 2),
('Carl', 'B', 3),
('John', 'C', 100),
('John', 'C', 200),
('John', 'C', 300)
)
select *,
case
when category in ('A','B')
and bool_or(exam_id in (44, 55, 88)) over (partition by student) then 'A'
else category
end as adjusted_category
from my_table;
db<>fiddle here