SQL ORACLE Select the top-N rows using join

Question

Find the cats occupying the first n places in terms of the total number of mice consumed (cats with the same consumption occupy the same place!) using the join of the Kocury relation with the Kocury relation .

[this solution doesn't quite work properly] When n=1 there are two cats (Tygrys and Lysy), but should be only Tygrys.

I have 3 correct solutions but for my 4 one I have ot use JOIN operator or LEFT JOIN or sth related to JOIN:

solution 1.
SELECT pseudo, przydzial_myszy + NVL(myszy_extra, 0) "ZJADA"
FROM Kocury K
WHERE (SELECT COUNT(DISTINCT przydzial_myszy + NVL(myszy_extra, 0)) FROM Kocury`enter code here`
      WHERE przydzial_myszy + NVL(myszy_extra, 0) > K.przydzial_myszy + NVL(K.myszy_extra, 0)) < 6
ORDER BY 2 DESC;

solution 2
SELECT pseudo, przydzial_myszy + NVL(myszy_extra, 0) "ZJADA"
FROM Kocury
WHERE przydzial_myszy + NVL(myszy_extra, 0) IN (
  SELECT *
  FROM (
    SELECT DISTINCT przydzial_myszy + NVL(myszy_extra, 0)
    FROM Kocury
    ORDER BY 1 DESC
  ) WHERE ROWNUM <= 6
);

solution 3
SELECT pseudo, ZJADA
FROM
(
  SELECT pseudo,
    NVL(przydzial_myszy, 0) + NVL(myszy_extra, 0) "ZJADA",
    DENSE_RANK() OVER (
      ORDER BY przydzial_myszy + NVL(myszy_extra, 0) DESC
    ) RANK
  FROM Kocury
)
WHERE RANK <= 6;

[Kocury relation]

Answer 1

I don't quite understand column names so I'll suggest a query which is somewhat simpler to understand. Read comments within code.

with 
temp as
  (select cat_name,
     sum(mice_consumed) sum_mice
   from cats_mice
   group by cat_name
  ),
rank_cats as
  (select cat_name,
     sum_mice,
     dense_rank() over (order by sum_mice desc) rnk
   from temp
  )
-- finally:
select cat_name,
  sum_mice
from rank_cats
where rnk < 7;

Answer 2

You can use:

SELECT k.pseudo,
       MAX(k.przydzial_myszy) AS przydzial_myszy,
       MAX(k.myszy_extra) AS myszy_extra,
       MAX(k.przydzial_myszy + COALESCE(k.myszy_extra, 0)) AS total
FROM   Kocury k
       LEFT OUTER JOIN Kocury h
       ON (h.przydzial_myszy + COALESCE(h.myszy_extra, 0)
            > k.przydzial_myszy + COALESCE(k.myszy_extra, 0))
GROUP BY k.pseudo
HAVING COUNT(DISTINCT h.przydzial_myszy + COALESCE(h.myszy_extra, 0)) < 3
ORDER BY total DESC

Which for the sample data:

CREATE TABLE Kocury (pseudo, przydzial_myszy, myszy_extra) AS
SELECT 'PLACEK',   67, NULL FROM DUAL UNION ALL
SELECT 'RURA',     56, NULL FROM DUAL UNION ALL
SELECT 'LOLA',     25, 47   FROM DUAL UNION ALL
SELECT 'ZERO',     43, NULL FROM DUAL UNION ALL
SELECT 'PUSZYSTA', 20, 35   FROM DUAL UNION ALL
SELECT 'UCHO',     40, NULL FROM DUAL UNION ALL
SELECT 'MALY',     40, NULL FROM DUAL UNION ALL
SELECT 'TYGRYS',  103, 33   FROM DUAL UNION ALL
SELECT 'BOLEK',    50, NULL FROM DUAL UNION ALL
SELECT 'ZOMBI',    75, 13   FROM DUAL UNION ALL
SELECT 'LYSY',     72, 21   FROM DUAL UNION ALL
SELECT 'SZYBKA',   65, NULL FROM DUAL UNION ALL
SELECT 'MALA',     22, 42   FROM DUAL UNION ALL
SELECT 'RAFA',     65, NULL FROM DUAL;

Outputs:

PSEUDO	PRZYDZIAL_MYSZY	MYSZY_EXTRA	TOTAL
TYGRYS	103	33	136
LYSY	72	21	93
ZOMBI	75	13	88

db<>fiddle here