[SQL 문제 풀이] 특정 세대의 대장균 찾기

SELECT 
    A.ID
FROM 
    ECOLI_DATA AS A
JOIN 
    ECOLI_DATA AS B 
ON 
    A.PARENT_ID = B.ID
JOIN
    ECOLI_DATA AS C
ON
    B.PARENT_ID = C.ID
WHERE 
    C.PARENT_ID IS NULL
ORDER BY 
    ID;