leetcode数据库系列

511. 游戏玩法分析 I

# Write your MySQL query statement below
SELECT player_id, min(event_date) first_login
FROM Activity
GROUP BY player_id;

512. 游戏玩法分析 II

https://blog.csdn.net/weixin_44547599/article/details/88764558

SELECT
    player_id, 
    device_id
FROM
    (SELECT
        player_id,
        device_id,
        ROW_NUMBER() OVER(PARTITION BY player_id ORDER BY event_date) AS rn
    FROM
        Activity) AS a
WHERE 
    rn = 1;

175. 组合两个表

# Write your MySQL query statement below
SELECT FirstName, LastName, City, state
FROM Person LEFT JOIN Address
ON Person.PersonId = Address.PersonId
;

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