1251. 平均售价 - 力扣(LeetCode)
表:Prices
+---------------+---------+ | Column Name | Type | +---------------+---------+ | product_id | int | | start_date | date | | end_date | date | | price | int | +---------------+---------+ (product_id,start_date,end_date) 是prices
表的主键(具有唯一值的列的组合)。prices
表的每一行表示的是某个产品在一段时期内的价格。 每个产品的对应时间段是不会重叠的,这也意味着同一个产品的价格时段不会出现交叉。
表:UnitsSold
+---------------+---------+ | Column Name | Type | +---------------+---------+ | product_id | int | | purchase_date | date | | units | int | +---------------+---------+ 该表可能包含重复数据。 该表的每一行表示的是每种产品的出售日期,单位和产品 id。
编写解决方案以查找每种产品的平均售价。average_price
应该 四舍五入到小数点后两位。如果产品没有任何售出,则假设其平均售价为 0。
返回结果表 无顺序要求 。
结果格式如下例所示。
示例 1:
输入: Prices table: +------------+------------+------------+--------+ | product_id | start_date | end_date | price | +------------+------------+------------+--------+ | 1 | 2019-02-17 | 2019-02-28 | 5 | | 1 | 2019-03-01 | 2019-03-22 | 20 | | 2 | 2019-02-01 | 2019-02-20 | 15 | | 2 | 2019-02-21 | 2019-03-31 | 30 | +------------+------------+------------+--------+ UnitsSold table: +------------+---------------+-------+ | product_id | purchase_date | units | +------------+---------------+-------+ | 1 | 2019-02-25 | 100 | | 1 | 2019-03-01 | 15 | | 2 | 2019-02-10 | 200 | | 2 | 2019-03-22 | 30 | +------------+---------------+-------+ 输出: +------------+---------------+ | product_id | average_price | +------------+---------------+ | 1 | 6.96 | | 2 | 16.96 | +------------+---------------+ 解释: 平均售价 = 产品总价 / 销售的产品数量。 产品 1 的平均售价 = ((100 * 5)+(15 * 20) )/ 115 = 6.96 产品 2 的平均售价 = ((200 * 15)+(30 * 30) )/ 230 = 16.96
这道题的创建表的语句为
Create table If Not Exists Prices (product_id int, start_date date, end_date date, price int)
Create table If Not Exists UnitsSold (product_id int, purchase_date date, units int)
Truncate table Prices
insert into Prices (product_id, start_date, end_date, price) values ('1', '2019-02-17', '2019-02-28', '5')
insert into Prices (product_id, start_date, end_date, price) values ('1', '2019-03-01', '2019-03-22', '20')
insert into Prices (product_id, start_date, end_date, price) values ('2', '2019-02-01', '2019-02-20', '15')
insert into Prices (product_id, start_date, end_date, price) values ('2', '2019-02-21', '2019-03-31', '30')
Truncate table UnitsSold
insert into UnitsSold (product_id, purchase_date, units) values ('1', '2019-02-25', '100')
insert into UnitsSold (product_id, purchase_date, units) values ('1', '2019-03-01', '15')
insert into UnitsSold (product_id, purchase_date, units) values ('2', '2019-02-10', '200')
insert into UnitsSold (product_id, purchase_date, units) values ('2', '2019-03-22', '30')
这道题不会
我看答案了
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计算总销售额:
SUM(P.price * U.units) = 20.00 + 60.00 + 30.00 = 110.00
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计算总单位数:
SUM(U.units) = 2 + 3 + 1 = 6
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计算加权平均价格:
110.00 / 6 = 18.33
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四舍五入到两位小数:
ROUND(18.33, 2) = 18.33
SELECT
product_id,
IFNULL(Round(SUM(sales) / SUM(units), 2), 0) AS average_price
FROM (
SELECT
Prices.product_id AS product_id,
Prices.price * UnitsSold.units AS sales,
UnitsSold.units AS units
FROM Prices
LEFT JOIN UnitsSold ON Prices.product_id = UnitsSold.product_id
AND (UnitsSold.purchase_date BETWEEN Prices.start_date AND Prices.end_date)
) T
GROUP BY product_id