解答
171
SQL文(クエリ)
SELECT
AVG(DATE_DIFF("2019-12-31", birthday, YEAR)) AS avg_age
FROM
sample.customers
WHERE
DATE_DIFF("2019-12-31", birthday, YEAR) > (
SELECT
AVG(DATE_DIFF("2019-12-31", birthday, YEAR)) AS avg_age
FROM
sample.customers
)



