题目介绍: 重新格式化部门表 reformat-department-table
SQL架构
部门表
Department
:
+---------------+---------+
| Column Name | Type |
+---------------+---------+
| id | int |
| revenue | int |
| month | varchar |
+---------------+---------+
(id, month) 是表的联合主键。
这个表格有关于每个部门每月收入的信息。
月份(month)可以取下列值 ["Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"]。
编写一个 SQL 查询来重新格式化表,使得新的表中有一个部门 id 列和一些对应 每个月 的收入(revenue)列。
查询结果格式如下面的示例所示:
``` Department 表: +------+---------+-------+ | id | revenue | month | +------+---------+-------+ | 1 | 8000 | Jan | | 2 | 9000 | Jan | | 3 | 10000 | Feb | | 1 | 7000 | Feb | | 1 | 6000 | Mar | +------+---------+-------+
查询得到的结果表: +------+-------------+-------------+-------------+-----+-------------+ | id | Jan_Revenue | Feb_Revenue | Mar_Revenue | ... | Dec_Revenue | +------+-------------+-------------+-------------+-----+-------------+ | 1 | 8000 | 7000 | 6000 | ... | null | | 2 | 9000 | null | null | ... | null | | 3 | null | 10000 | null | ... | null | +------+-------------+-------------+-------------+-----+-------------+
注意,结果表有 13 列 (1个部门 id 列 + 12个月份的收入列)。 ```
sql
SELECT id,
SUM(CASE `month` WHEN 'Jan' THEN revenue END) Jan_Revenue,
SUM(CASE `month` WHEN 'Feb' THEN revenue END) Feb_Revenue,
SUM(CASE `month` WHEN 'Mar' THEN revenue END) Mar_Revenue,
SUM(CASE `month` WHEN 'Apr' THEN revenue END) Apr_Revenue,
SUM(CASE `month` WHEN 'May' THEN revenue END) May_Revenue,
SUM(CASE `month` WHEN 'Jun' THEN revenue END) Jun_Revenue,
SUM(CASE `month` WHEN 'Jul' THEN revenue END) Jul_Revenue,
SUM(CASE `month` WHEN 'Aug' THEN revenue END) Aug_Revenue,
SUM(CASE `month` WHEN 'Sep' THEN revenue END) Sep_Revenue,
SUM(CASE `month` WHEN 'Oct' THEN revenue END) Oct_Revenue,
SUM(CASE `month` WHEN 'Nov' THEN revenue END) Nov_Revenue,
SUM(CASE `month` WHEN 'Dec' THEN revenue END) Dec_Revenue
FROM Department
GROUP BY id;
```sql 1193. 每月交易 I SQL架构 Table: Transactions
+---------------+---------+ | Column Name | Type | +---------------+---------+ | id | int | | country | varchar | | state | enum | | amount | int | | trans_date | date | +---------------+---------+ id 是这个表的主键。 该表包含有关传入事务的信息。 state 列类型为 “[”批准“,”拒绝“] 之一。
编写一个 sql 查询来查找每个月和每个国家/地区的事务数及其总金额、已批准的事务数及其总金额。
查询结果格式如下所示:
Transactions table: +------+---------+----------+--------+------------+ | id | country | state | amount | trans_date | +------+---------+----------+--------+------------+ | 121 | US | approved | 1000 | 2018-12-18 | | 122 | US | declined | 2000 | 2018-12-19 | | 123 | US | approved | 2000 | 2019-01-01 | | 124 | DE | approved | 2000 | 2019-01-07 | +------+---------+----------+--------+------------+
Result table: +----------+---------+-------------+----------------+--------------------+-----------------------+ | month | country | trans_count | approved_count | trans_total_amount | approved_total_amount | +----------+---------+-------------+----------------+--------------------+-----------------------+ | 2018-12 | US | 2 | 1 | 3000 | 1000 | | 2019-01 | US | 1 | 1 | 2000 | 2000 | | 2019-01 | DE | 1 | 1 | 2000 | 2000 | +----------+---------+-------------+----------------+--------------------+-----------------------+ ```
sql
SELECT DATE_FORMAT(trans_date, '%Y-%m') AS month,
country,
COUNT(*) AS trans_count,
COUNT(IF(state = 'approved', 1, NULL)) AS approved_count,
SUM(amount) AS trans_total_amount,
SUM(IF(state = 'approved', amount, 0)) AS approved_total_amount
FROM Transactions
GROUP BY month, country