## Country

id | name
--- | ---
1 | USA
2 | UK

## Central_Bank

id | central_bank_name | country_id
--- | --- | ---
|  | (→ Country.id)
1 | Federal Reserve | 1
2 | Bank of England | 2

## Commercial_Bank

id | commercial_bank_name | country_id
--- | --- | ---
|  | (→ Country.id)
1 | Citibank | 1
2 | Barclays | 2

## Account

id | account_number | balance | commercial_bank_id
--- | --- | --- | ---
|  |  | (→ Commercial_Bank.id)
1 | 123456789 | 0 | 1
2 | 987654321 | 0 | 2