-- 점수 순위 매기기
SELECT SCORE AS SCORE , DENSE_RANK() OVER(ORDER BY SCORE DESC) AS RANK
FROM SCORES
SELECT A.ID, COUNT(B.PARENT_ID) AS CHILD_COUNT FROM ECOLI_DATA A LEFT OUTER JOIN (
SELECT PARENT_ID
FROM ECOLI_DATA
) B
ON A.ID = B.PARENT_ID
GROUP BY A.ID
ID를 부모ID와 연결짖기