leetcode1193. 每月交易 I 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。
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 |
+----------+---------+-------------+----------------+---------------
来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/monthly-transactions-i
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此题不难
代码
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
date_format
DATE_FORMAT() 函数用于以不同的格式显示日期/时间数据。
DATE_FORMAT(date,format)
date_format(date, '%Y-%m')
此处的Y如果是大写，则为完整年份，如2018，如为小写，则为年份的后面两位，如18
count(if(state="approved",1,null))
sum(if(state="approved",amount,0))
本文地址：https://blog.csdn.net/weixin_42764993/article/details/107647557