Find the Latest Balance for a Bank Account

Write a PostgreSQL query that returns the latest reported balance for one bank account. ### Tables `bank_balances(bank_name text, account_name text, start_date date, end_date date, balance numeric(18,2))` `requested_account(bank_name text, account_name text)` contains exactly one row. ### Rules - Match both bank name and account name exactly. Account names are text identifiers and may contain leading zeros. - For this exercise, latest means greatest `end_date`; each bank/account pair has at most one row with a given end date. - Every field is non-null, and `start_date <= end_date`. - Records may span different months and years. Dates are typed dates, not strings to compare lexicographically. ### Output Return one column named `balance` for the latest matching record. If the requested account has no record, return no rows. The end-date definition and missing-account behavior are explicit exercise conventions. ### Example `bank_balances`: | bank_name | account_name | start_date | end_date | balance | |---|---|---|---|---:| | Harbor | 001234 | 2021-12-01 | 2021-12-31 | 150.00 | | Harbor | 001234 | 2019-05-01 | 2019-05-31 | 200.00 | | Bay | 001234 | 2022-01-01 | 2022-01-31 | 300.00 | `requested_account`: `('Harbor', '001234')` Expected output: | balance | |---:| | 150.00 |