Top Patients by Appointment Frequency | Dataford Interview Questions

Write a SQL query to find the top 10 patients by appointment frequency at PatientPoint.

Count only completed and scheduled appointments. Exclude cancelled and no-show appointments, as well as appointments without a matching patient record.

Output

One row per qualifying patient, with patient_id, full_name, and appointment_count.
Return at most 10 patients, ordered by appointment_count descending and patient_id ascending to break ties.
Rows without a matching patient record are ignored.

Schema

patients

Column	Type	Description
patient_idPK	INTEGER	Unique patient identifier
full_name	VARCHAR(200)	Patient's full name
date_of_birth	DATE	Patient date of birth

appointments

Column	Type	Description
appointment_idPK	INTEGER	Unique appointment identifier
patient_id	INTEGER	Patient associated with the appointment
appointment_date	DATE	Date of the appointment
status	VARCHAR(20)	Appointment status

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Problem