SQL for Failed Transactions Window | Dataford Interview Questions

Given a dataset of transactional records, write a SQL query to identify customers who have had more than three failed transactions within a 24-hour window at Paddle.

Return the earliest qualifying window for each customer. Treat the 24-hour boundary as inclusive and ignore transactions that are not failed.

Output

One row per qualifying customer with customer_id, window_start, window_end, and failed_transaction_count.
Order by customer_id.

Schema

transactions

Column	Type	Description
transaction_idPK	INT	Unique Paddle transaction identifier
customer_id	VARCHAR(30)	Paddle customer identifier
status	VARCHAR(20)	Transaction outcome, such as failed or succeeded
occurred_at	TIMESTAMPTZ	Timestamp when the transaction occurred

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