力扣sql入门篇(八)

1 订单最多的客户

1.1 题目内容

1.1.1 基本题目信息

1.1.2 示例输入输出

1.2 示例sql语句

SELECT customer_number
FROM Orders
GROUP BY customer_number
having count(order_number)=(
    SELECT max(o1.number)
    FROM (
        SELECT count(order_number) number
        FROM Orders
        GROUP BY customer_number
    ) o1   
)

1.3 运行截图

2 游戏玩法分析I

2.1 题目内容

2.1.1 基本题目信息

2.1.2 示例输入输出

2.2 示例sql语句

SELECT player_id,min(event_date) first_login
FROM Activity
GROUP BY player_id;

2.3 运行截图

3 2020年最后一次登录

3.1 题目内容

3.1.1 基本题目信息

3.1.2 示例输入输出

3.2 示例sql语句

# ①先筛选出2020年的所有用户②再去分组筛选出来
select L1.user_id,MAX(L1.time_stamp) last_stamp
FROM
(
    SELECT *
    FROM Logins
    WHERE DATE_FORMAT(time_stamp,"%Y")=2020
) L1
GROUP BY L1.user_id;

3.3 运行截图

4 查找每个员工花费的总时间

4.1 题目内容

4.1.1 基本题目信息

4.1.2 示例输入输出

4.2 示例sql语句

SELECT e1.event_day day,e1.emp_id emp_id,sum(e1.differ_value) total_time
FROM
(
    SELECT emp_id,event_day,out_time-in_time differ_value
    FROM Employees
) e1
GROUP BY e1.emp_id,e1.event_day;

4.3 运行截图