力扣sql中等篇练习(十二)

1 产品销售分析 |||

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

# Write your MySQL query statement below
SELECT s1.product_id,s1.first_year,s2.quantity,s2.price
FROM
(
    SELECT product_id,Min(year) first_year
    FROM Sales
    GROUP BY product_id
)s1
INNER JOIN Sales s2
ON s1.product_id=s2.product_id AND s1.first_year=s2.year

1.3 运行截图

2 小众书籍

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

# 要注意筛选掉今日之后的日期
# 分组之后是不可用IFNULL函数
SELECT  b.book_id,b.name
FROM
(
    SELECT *
    FROM Books
    WHERE DATEDIFF('2019-06-23',available_from) >=30
)b
LEFT JOIN 
(
    SELECT *
    FROM Orders
    WHERE dispatch_date between date_sub('2019-06-23',interval 1 year) and dispatch_date
)o
ON b.book_id=o.book_id
GROUP BY b.book_id
HAVING IFNULL(sum(o.quantity),0)<10

2.3 运行截图

3 每日新用户统计

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

# 找到符合条件的最少时间的的记录
# 求时间查值用DATEDIFF函数 已知日期-日期字段
# 具体天数最好用SDATEDIFF函数
SELECT t1.mDate login_date,count(user_id) user_count
FROM
(
    SELECT user_id,min(activity_date) mDate
    FROM Traffic
    WHERE activity='login'
    GROUP BY user_id
)t1
WHERE DATEDIFF('2019-06-30',t1.mDate)<=90
GROUP BY t1.mDate
ORDER BY user_count asc,t1.mDate asc

3.3 运行截图