medium30 ptsRunning Totals Window Functions

Ledger Running Balance

ledger_entries holds credits (positive amount) and debits (negative amount) for each account. Several entries can share a date; within a date, entries apply in entry_id order.

For every entry, show the account's running balance after that entry, rounded with ROUND(x, 2).

Return columns account_id, entry_date, entry_id, running_balance. Order by account_id, then entry_date, then entry_id, all ascending.

Schema

CREATE TABLE ledger_entries (
  entry_id INTEGER PRIMARY KEY,
  account_id INTEGER NOT NULL,
  entry_date TEXT NOT NULL,
  amount REAL NOT NULL
);

Sample data

ledger_entries

entry_id	account_id	entry_date	amount
1	100	2026-01-01	1000
2	100	2026-01-03	-250
3	200	2026-01-02	500
4	100	2026-01-05	-100.5
5	200	2026-01-04	-600
6	200	2026-01-06	300

Hint 1

SUM(...) OVER (PARTITION BY account ORDER BY ...) gives a cumulative sum per account.

Hint 2

An entry_id can be smaller than an earlier-dated entry, so order the window by date first, then id.

Good practice for: Data Analyst, Backend Developer, Data Engineer, Database Administrator

SQL (SQLite)

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