SQL for 7-Day Test Start | Dataford Interview Questions

Your question is SQL for 7-Day Test Start. Start with the requirements and the three tables on the right.

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Problem

Turing's Product Growth team wants to identify candidates who completed their Turing profile but did not start the technical test within seven days of completion. Write a PostgreSQL query using the earliest profile completion per user.

Requirements

Return each matching user's ID, name, and earliest profile completion timestamp.
Exclude users who started any technical test from the completion timestamp through seven days afterward, inclusive.
Include users with no technical test record, and sort results by profile completion time and user ID.

Schema

users

Column	Type	Description
user_idPK	INT	Candidate identifier
full_name	VARCHAR(100)	Candidate full name
email	VARCHAR(255)	Candidate email address
joined_at	TIMESTAMP	Account creation timestamp

profile_completions

Column	Type	Description
completion_idPK	INT	Profile completion event identifier
user_id	INT	Candidate associated with the completion
completed_at	TIMESTAMP	Profile completion timestamp

technical_test_starts

Column	Type	Description
test_start_idPK	INT	Technical test start event identifier
user_id	INT	Candidate who started the test
started_at	TIMESTAMP	Technical test start timestamp
test_name	VARCHAR(100)	Name of the Turing technical test