Code RoomBoth sides of every transaction
MediumPrep Room Coding #5100

Both sides of every transaction

SQLAlgorithms & data structuresMid~11 min

Return each transaction with the accounts it touched. Give `txn_id`, `account` and `amount_cents`, ordered by transaction then account.

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 11 min

Expected, in this order

txn_idaccountamount_cents
100Cash50000
100Revenue-50000
101Cash-1500
101Fees1500
102Cash32000
102Revenue-32000

2 more rows

Your result

Run your query to compare.

1 more set of rows are waiting. Free with an account.