Oracle query to match all values in the list among all rows in table

Question

I have a table structure as under:

ID    A     B
--   ---  -----
 1    a     a1
 2    b     b1
 3    a     a2
 4    c     a1
 5    b     b2

Answer 1

Use a GROUP BY and a COUNT.

SELECT A
FROM yourtable
WHERE B IN ('a1', 'a2')
GROUP BY A
HAVING Count(DISTINCT B) > 1