How to aggregate data by SQL?

I am not a SQL developer, but I need to make a request to sample the movement of accounts for the last month, aggregate information by client country.

I could only create an sample database but I have no idea what to do next.

Answer

Your question isn’t totally clear what you are looking for, but you will need to use an aggregate function like SUM or COUNT as well as using a GROUP BY depending on what you need.

Here is a sum of the amount of transactions by country as an example.

select country, sum(transactions.amount) as TOTAL_AMT
from clients as clients
inner join accounts as accounts
  on accounts.client_id = clients.client_id
inner join transactions as transactions
  on transactions.sender_account_id = accounts.account_id
group by country;