Daily Closing Balance

Given transactions per date, return each date with the closing balance (cumulative sum up to and including that date). Order by date.

Table schema

Txns(txn_date DATE, amount INT)

Sample data

txn_date | amount
2026-05-01 | 100
2026-05-01 | -40
2026-05-02 | 30
2026-05-04 | -50