SQL for Clinical Criteria | Dataford Interview Questions

Write a SQL query to extract patient records that meet these three specific clinical criteria.

For this exercise, identify patients under 18 as of January 1, 2025, with an asthma encounter showing oxygen saturation below 92%, and an active albuterol prescription. Return one row per qualifying patient and use only records satisfying all three criteria.

Output

Return patient_id, patient_name, and latest_qualifying_encounter.
Sort by patient_id ascending.

Schema

patients

Column	Type	Description
patient_idPK	INT	Unique patient identifier
patient_name	VARCHAR(100)	Patient display name
date_of_birth	DATE	Patient date of birth

encounters

Column	Type	Description
encounter_idPK	INT	Unique encounter identifier
patient_id	INT	Patient associated with the encounter
encounter_date	DATE	Date of clinical encounter
diagnosis_code	VARCHAR(20)	Diagnosis code recorded for the encounter
oxygen_saturation	INT	Oxygen saturation percentage

medications

Column	Type	Description
medication_idPK	INT	Unique medication record identifier
patient_id	INT	Patient associated with the prescription
medication_name	VARCHAR(100)	Medication name
status	VARCHAR(20)	Prescription status

Your question is SQL for Clinical Criteria. Start with the requirements and the three tables in the Question tab.

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Problem