Selecting min count('x') by year - sql

Question

I'm trying to create a table that displays the song(s) with the minimum number of plays by year.
For instance if Song1 and Song2 both only had 1 play and Song3 had 2 plays in 2018 and Song1 had 1 play in 2017 and Song2 had 2 plays in 2017, I want a table that would return 3 rows:
Song1 - 2018 - 1 play Song2 - 2018 - 1 play
Song1 - 2017 - 1 play
Is there a way to display the songs where min(count('x')) = count('x').
I'm sure that isn't the proper syntax but it's essentially what I'm trying to find.
SELECT * FROM music
NATURAL JOIN (SELECT extract(year from date) AS yr, song_code, COUNT('x')
FROM singles NATURAL JOIN plays
GROUP BY extract(year from date), song_code
ORDER BY yr desc, COUNT('x') desc);
Currently I have the songs grouped by number of plays a year, but I'm not sure how to only show those that have played the minimum amount of times.

Answer 1

-- You can prefer using analytic functions such as dense_rank() rather than joins or in-subqueries.
with songs( id, year, play_id ) as
(
select 1, 2018, 1 from dual union all
select 2, 2018, 1 from dual union all
select 3, 2018, 1 from dual union all
select 3, 2018, 2 from dual union all
select 1, 2017, 1 from dual union all
select 2, 2017, 1 from dual union all
select 2, 2017, 2 from dual
)
select id, year, play_cnt
from
(select s.*, dense_rank() over (partition by year order by play_cnt) dr
from
(select id, year, count(play_id) as play_cnt
from songs s
group by id, year
) s
)
where dr = 1;
ID YEAR PLAY_CNT
---------- ---------- ----------
1 2017 1
2 2018 1
1 2018 1

Answer 2

This should work. This is also a good example of why we should use WITH (subquery factoring) instead of an inline view. creating a song_count subquery factoring with year, song_code and count.
Also, I would explicitly define the joins for clarity
WITH song_count as
SELECT extract(year from date) AS song_year, song_code, count(*) as play_count
FROM singles NATURAL JOIN plays
group by extract(year from date),song_code
select * from song_count
where
(song_year,play_count) in (select song_year,min(play_count) from song_count group by song_year)

Answer 3

You can try with row_number():
SELECT *
FROM music
NATURAL JOIN
(select yr, song_code, play_count
from
(SELECT extract(year from date) AS yr, song_code, COUNT('x') play_count, row_number() over (partition by extract(year from date), song_code order by COUNT('x')) rn
FROM singles NATURAL JOIN plays
GROUP BY extract(year from date), song_code
)
where rn = 1;