Consecutive Missed Visits in SQL | Dataford Interview Questions

Write a SQL query to identify patients who have missed two consecutive clinical visits based on this event log table.

Use only rows representing clinical visits. Consecutive means adjacent scheduled clinical visits for the same patient when ordered chronologically.

Output

One row per qualifying patient, with patient_id, first_missed_visit_date, and second_missed_visit_date.
Return the earliest qualifying pair for each patient, ordered by patient_id.

event_log

Column	Type	Description
event_idPK	INT	Unique event identifier
patient_id	INT	Patient associated with the event
event_type	VARCHAR(50)	Type of recorded event
visit_date	DATE	Scheduled date of the clinical visit
visit_status	VARCHAR(30)	Outcome status of the visit

Your question is Consecutive Missed Visits in SQL. Start with the requirements and the one table 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.

Write a SQL query to identify patients who have missed two consecutive clinical visits based on this event log table.

Use only rows representing clinical visits. Consecutive means adjacent scheduled clinical visits for the same patient when ordered chronologically.

One row per qualifying patient, with patient_id, first_missed_visit_date, and second_missed_visit_date.
Return the earliest qualifying pair for each patient, ordered by patient_id.

event_log

Column	Type	Description
event_idPK	INT	Unique event identifier
patient_id	INT	Patient associated with the event
event_type	VARCHAR(50)	Type of recorded event
visit_date	DATE	Scheduled date of the clinical visit
visit_status	VARCHAR(30)	Outcome status of the visit

Your question is Consecutive Missed Visits in SQL. Start with the requirements and the one table 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.