TIL - 250206

리뷰 : 윈도우 함수를 기억하는 하루

URL : https://datalemur.com/questions/frequent-callers

SELECT
  COUNT(policy_holder_id)
FROM (
SELECT
  policy_holder_id
  ,COUNT(case_id) cnt
FROM callers
GROUP BY 1
) a
WHERE cnt >= 3
;

URL : https://datalemur.com/questions/sql-third-transaction

SELECT
  user_id, spend, transaction_date
FROM (
SELECT 
  *
  ,ROW_NUMBER() OVER(PARTITION BY user_id ORDER BY transaction_date)
FROM transactions
) a
WHERE row_number =3
;