Country

idname
1USA
2UK

Central_Bank

idcentral_bank_namecountry_id
(→ Country.id)
1Federal Reserve1
2Bank of England2

Commercial_Bank

idcommercial_bank_namecountry_id
(→ Country.id)
1Citibank1
2Barclays2

Account

idaccount_numberbalancecommercial_bank_id
(→ Commercial_Bank.id)
112345678901
298765432102