[LeetCode] Market Analysis I

Source

• https://leetcode.com/problems/market-analysis-i/

Market Analysis I - LeetCode

 

문제

• 2019년도에 주문 이력이 있는 user_id와 join_date 그리고 주문 총합을 구하는 쿼리 작성

 

Solution (MySQL)

SELECT user_id AS buyer_id, join_date, COUNT(order_id) AS orders_in_2019
FROM Users AS u
LEFT OUTER JOIN 
  (
    SELECT order_id, buyer_id
    FROM Orders
    WHERE DATE_FORMAT(order_date, "%Y") = "2019"
  ) AS o
ON user_id = buyer_id
GROUP BY user_id;