Formatted question description: https://leetcode.ca/all/1193.html
1193. Monthly Transactions I
Level
Medium
Description
Table: Transactions
+---------------+---------+
| Column Name | Type |
+---------------+---------+
| id | int |
| country | varchar |
| state | enum |
| amount | int |
| trans_date | date |
+---------------+---------+
id is the primary key of this table.
The table has information about incoming transactions.
The state column is an enum of type ["approved", "declined"].
Write an SQL query to find for each month and country, the number of transactions and their total amount, the number of approved transactions and their total amount.
The query result format is in the following example:
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 |
+----------+---------+-------------+----------------+--------------------+-----------------------+
Solution
Use date_format(trans_date, '%Y-%m')
to obtain the month of each transaction. For trans_count
and trans_total_amount
, simply use count
and sum
to obtain the values. For approved_count
and approved_total_amount
, use if
statement to obtain the values. The query result is grouped by month
and country
.
# Write your MySQL query statement below
select date_format(trans_date, '%Y-%m') as month, country, count(*) as trans_count,
sum(if(state = 'approved', 1, 0)) as approved_count, sum(amount) as trans_total_amount,
sum(if(state = 'approved', amount, 0)) as approved_total_amount
from Transactions
group by date_format(trans_date, '%Y-%m'), country;