[SQL] 특정 세대의 대장균 찾기

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정답 쿼리

WITH G1 AS (
    SELECT ID, PARENT_ID
    FROM ECOLI_DATA
    WHERE PARENT_ID IS NULL
),

G2 AS (
    SELECT ID, PARENT_ID
    FROM ECOLI_DATA
    WHERE PARENT_ID IN (SELECT ID FROM G1)
),

G3 AS (
    SELECT ID
    FROM ECOLI_DATA
    WHERE PARENT_ID IN (SELECT ID FROM G2)
)

SELECT * FROM G3