레스토랑의 요일별 VIP & 데이터 그룹으로 묶기 (solvesql)

레스토랑의 요일별 VIP

https://solvesql.com/problems/restaurant-vip/

SELECT *
FROM tips
WHERE total_bill IN(SELECT MAX(total_bill) FROM tips GROUP BY day)

데이터 그룹으로 묶기

https://solvesql.com/problems/group-by/

variance() - > 표준 편차를 구하는 함수입니다.

SELECT
  quartet,
  round(avg(x), 2) AS x_mean,
  round(variance(x), 2) AS x_var,
  round(avg(y), 2) AS y_mean,
  round(variance(y), 2) AS y_var
FROM points
GROUP BY quartet