Records Missing From Another Table | Dataford Interview Questions

Revature needs to identify active QA Engineer candidates who have not submitted the required PostgreSQL assessment in the Revature learning platform. Write a PostgreSQL query that finds candidates present in the candidate roster but absent from the required assessment submissions.

Requirements

Return only active candidates whose track is QA Engineer.
Identify candidates with no submission for assessment code POSTGRESQL-BASICS.
Return candidate_id, full_name, and track, ordered by candidate_id ascending.

Place the assessment-code condition in the join logic so that submissions for other assessments do not incorrectly count as matches.

Schema

qa_candidates

Column	Type	Description
candidate_idPK	INT	Unique candidate identifier
full_name	VARCHAR(100)	Candidate's full name
track	VARCHAR(50)	Assigned Revature training track
is_active	BOOLEAN	Whether the candidate is currently active

qa_assessment_submissions

Column	Type	Description
submission_idPK	INT	Unique assessment submission identifier
candidate_id	INT	Candidate associated with the submission
assessment_code	VARCHAR(50)	Submitted assessment code
submitted_at	DATE	Date the assessment was submitted
score	INT	Assessment score when grading is complete

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Problem