Multiple Admissions Same Month | Dataford Interview Questions

Your question is Multiple Admissions Same Month. Start with the requirements and the two tables on the right.

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Problem

Providence patient encounter reporting needs to flag patients with repeated inpatient admissions during the same calendar month. Write a PostgreSQL query using the patients and admissions tables.

Requirements

Return each qualifying patient's ID and name, the calendar month, and the number of admissions.
Include a comma-separated, chronologically ordered list of admission IDs for that patient and month.
Return only patient-month groups with at least two admissions, excluding admissions with a missing admission timestamp.
Order results by admission month and patient ID.

Schema

patients

Column	Type	Description
patient_idPK	INTEGER	Unique patient identifier
full_name	VARCHAR(100)	Patient's full name
birth_date	DATE	Patient's date of birth

admissions

Column	Type	Description
admission_idPK	INTEGER	Unique admission identifier
patient_id	INTEGER	Patient associated with the admission
admitted_at	TIMESTAMP	Admission timestamp
discharge_date	DATE	Discharge date when available
admission_type	VARCHAR(30)	Admission classification