Code RoomA running cash balance
HardPrep Room Coding #5099

A running cash balance

SQLAlgorithms & data structuresSenior–Staff~15 min

Return the Cash entries in date order with the balance after each. Give `booked_on`, `amount_cents` and `balance_after`.

What a strong answer looks like

Say what the query is meant to return before you write it, and name the shape of the answer: how many rows, grouped by what. Then watch the NULLs and the duplicates, because that is where most of these are lost.

Run onlyA query runs as one statement, so there is nothing to step through. Run it and read the rows.

0:00 of about 15 min

Expected, in this order

booked_onamount_centsbalance_after
2026-01-055000050000
2026-01-05-150048500
2026-02-093200080500
2026-02-20-800072500

Your result

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