Today데이터 분석 온보딩 과제 Today I Learned SQL 1. 첫 코칭 신청 이후, 다음 코칭을 받기 까지의 평균 기간WITH r AS ( SELECT userid , createdat , ROW_NUMBER() OVER (PARTITION BY userid ORDER BY createdat ASC) AS rnk FROM data_set WHERE result != 'cancel' ), c AS ( SELECT userid , MAX(CASE WHEN rnk = 1 THEN createdat ELSE 0 END) AS first_createdat ..