add 1384

Author: fishercoder1534

README.md

@@ -929,6 +929,7 @@ _If you like this project, please leave me a star._ ★
 
 |  #  |      Title     |   Solutions   | Video         | Difficulty    | Tag          
 |-----|----------------|---------------|---------------|---------------|-------------
+|1384|[Total Sales Amount by Year](https://leetcode.com/problems/total-sales-amount-by-year/)|[Solution](../master/database/_1384.sql) || Hard |
 |1378|[Replace Employee ID With The Unique Identifier](https://leetcode.com/problems/replace-employee-id-with-the-unique-identifier/)|[Solution](../master/database/_1378.sql) || Easy |
 |1369|[Get the Second Most Recent Activity](https://leetcode.com/problems/get-the-second-most-recent-activity/)|[Solution](../master/database/_1369.sql) || Hard |
 |1364|[Number of Trusted Contacts of a Customer](https://leetcode.com/problems/number-of-trusted-contacts-of-a-customer/)|[Solution](../master/database/_1364.sql) || Medium |

database/_1384.sql

@@ -0,0 +1,89 @@
+--1384. Total Sales Amount by Year
+--
+--Table: Product
+--
+--+---------------+---------+
+--| Column Name   | Type    |
+--+---------------+---------+
+--| product_id    | int     |
+--| product_name  | varchar |
+--+---------------+---------+
+--product_id is the primary key for this table.
+--product_name is the name of the product.
+--
+--
+--Table: Sales
+--
+--+---------------------+---------+
+--| Column Name         | Type    |
+--+---------------------+---------+
+--| product_id          | int     |
+--| period_start        | varchar |
+--| period_end          | date    |
+--| average_daily_sales | int     |
+--+---------------------+---------+
+--product_id is the primary key for this table.
+--period_start and period_end indicates the start and end date for sales period, both dates are inclusive.
+--The average_daily_sales column holds the average daily sales amount of the items for the period.
+--
+--Write an SQL query to report the Total sales amount of each item for each year, with corresponding product name, product_id, product_name and report_year.
+--
+--Dates of the sales years are between 2018 to 2020. Return the result table ordered by product_id and report_year.
+--
+--The query result format is in the following example:
+--
+--
+--Product table:
+--+------------+--------------+
+--| product_id | product_name |
+--+------------+--------------+
+--| 1          | LC Phone     |
+--| 2          | LC T-Shirt   |
+--| 3          | LC Keychain  |
+--+------------+--------------+
+--
+--Sales table:
+--+------------+--------------+-------------+---------------------+
+--| product_id | period_start | period_end  | average_daily_sales |
+--+------------+--------------+-------------+---------------------+
+--| 1          | 2019-01-25   | 2019-02-28  | 100                 |
+--| 2          | 2018-12-01   | 2020-01-01  | 10                  |
+--| 3          | 2019-12-01   | 2020-01-31  | 1                   |
+--+------------+--------------+-------------+---------------------+
+--
+--Result table:
+--+------------+--------------+-------------+--------------+
+--| product_id | product_name | report_year | total_amount |
+--+------------+--------------+-------------+--------------+
+--| 1          | LC Phone     |    2019     | 3500         |
+--| 2          | LC T-Shirt   |    2018     | 310          |
+--| 2          | LC T-Shirt   |    2019     | 3650         |
+--| 2          | LC T-Shirt   |    2020     | 10           |
+--| 3          | LC Keychain  |    2019     | 31           |
+--| 3          | LC Keychain  |    2020     | 31           |
+--+------------+--------------+-------------+--------------+
+--LC Phone was sold for the period of 2019-01-25 to 2019-02-28, and there are 35 days for this period. Total amount 35*100 = 3500.
+--LC T-shirt was sold for the period of 2018-12-01 to 2020-01-01, and there are 31, 365, 1 days for years 2018, 2019 and 2020 respectively.
+--LC Keychain was sold for the period of 2019-12-01 to 2020-01-31, and there are 31, 31 days for years 2019 and 2020 respectively.
+--
+
+/* Write your T-SQL query statement below */
+--credit: https://leetcode.com/problems/total-sales-amount-by-year/discuss/544812/Using-Recursive-CTE-to-get-all-the-possible-dates
+
+with dates as
+(select s_date =  min(period_start), e_date = max(period_end) from sales
+	union all
+ select dateadd(day, 1 ,s_date) , e_date from dates
+ where s_date<e_date
+)
+select
+PRODUCT_ID  = cast(p.product_id  as varchar(200))
+,PRODUCT_NAME = p.product_name
+,REPORT_YEAR = cast(year(s_date) as varchar(10))
+,TOTAL_AMOUNT = sum(average_daily_sales)
+from product p
+left outer join sales s on p.product_id = s.product_id
+left outer join dates d on d.s_date between s.period_start and s.period_end
+group by p.product_id , p.product_name, year(s_date)
+order by 1,3
+option(maxrecursion 0)