SQL High-Level Topic Quiz | Dataford Interview Questions

Tell me about high-level SQL topics you’ve worked with, including how you approach writing and validating queries.

For the practical portion, write a query that identifies qualifying sites for active studies and demonstrates how you would validate the result. Include only sites with at least two completed enrollment events.

Output

One row per qualifying site, with study_name, site_name, total_participants, latest_event_date, and study_site_rank.
Include only active studies and qualifying sites, ordered by study_name, then study_site_rank, then site_id.

Schema

studies

Column	Type	Description
study_idPK	INT	Unique study identifier
study_name	VARCHAR(100)	Study display name
status	VARCHAR(20)	Study lifecycle status

sites

Column	Type	Description
site_idPK	INT	Unique site identifier
study_id	INT	Study associated with the site
site_name	VARCHAR(100)	Site display name

enrollment_events

Column	Type	Description
event_idPK	INT	Unique enrollment event identifier
site_id	INT	Site associated with the event
event_date	DATE	Date of the enrollment event
participant_count	INT	Participants represented by the event
event_status	VARCHAR(20)	Enrollment event status

Your question is SQL High-Level Topic Quiz. Start with the requirements and the three tables in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem