1. 두 테이블 결합하기SELECT DISTINCT(records.athlete_id) AS athlete_id FROM records INNER JOIN events ON records.event_id = events.idWHERE events.sport = 'Golf'2. 레스토랑 웨이터의 팁 분석SELECT day, time, ROUND(AVG(tip), 2) AS avg_tip, ROUND(AVG(size), 2) AS avg_sizeFROM tipsGROUP BY day, timeORDER BY day ASC, time ASC;3. 일별 블로그 방문자 수 집계SELECT event_date_kst AS dt, COUNT(DISTINCT user_pseudo_id) A..