SQL for Signup and No-Stream Users | Dataford Interview Questions

A music platform wants to identify recently registered users who have not streamed any audio. Write a PostgreSQL query to return users who signed up within the last 30 days relative to September 15, 2026, and have no associated stream events.

Output

One row per qualifying user, with columns user_id, email, and signup_at
Include signups from August 16, 2026 through September 15, 2026, inclusive, and exclude users with any matching audio stream
Rows with a NULL signup_at do not qualify. Rows with NULL email remain eligible when the other conditions are met.
Sort by signup_at descending, then user_id ascending as a tie-breaker

Schema

users

Column	Type	Description
user_idPK	INT	Unique user identifier
email	VARCHAR(255)	User email address
signup_at	TIMESTAMP	Timestamp when the user signed up

audio_streams

Column	Type	Description
stream_idPK	INT	Unique stream event identifier
user_id	INT	User who generated the stream event
audio_content_id	INT	Identifier of the streamed audio content
streamed_at	TIMESTAMP	Timestamp of the stream event

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Problem