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SQL Inner Join for Appointments
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SQL Inner Join for Appointments

MediumSQL · PostgreSQL

Problem

Write a SQL query using an inner join to find all patients who have had more than three appointments in the last month.

Treat "last month" as the rolling period from one month before the current date through the current date.

Output

  1. Return one row per qualifying patient with patient_id, patient_name, and appointment_count.
  2. Include only patients with more than three appointments in that period.
  3. Order by appointment_count descending, then patient_id ascending.

Schema

patients
ColumnTypeDescription
patient_idPKINTUnique patient identifier
patient_nameVARCHAR(100)Patient's full name
appointments
ColumnTypeDescription
appointment_idPKINTUnique appointment identifier
patient_idINTPatient associated with the appointment
appointment_dateDATEDate of the appointment
statusVARCHAR(20)Appointment status
Tablespatientsappointments
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