SQL Exercise: Patients with their doctors and medications

SQL hospital Database: Exercise-20 with Solution

20. From the following tables, write a SQL query to identify patients who have made an advanced appointment. Return Patient name as "Patient", Physician name as "Physician" and Medication name as "Medication".

Sample table: patient

Sample table: prescribes

Sample table: physician

Sample table: medication

Sample Solution:

SELECT t.name AS "Patient",
       p.name AS "Physician",
       m.name AS "Medication"
FROM patient t
JOIN prescribes s ON s.patient=t.ssn
JOIN physician p ON s.physician=p.employeeid
JOIN medication m ON s.medication=m.code
WHERE s.appointment IS NOT NULL;

Sample Output:

  Patient   |  Physician  |  Medication
------------+-------------+--------------
 John Smith | John Dorian | Procrastin-X
 Dennis Doe | Molly Clock | Thesisin
(2 rows)

Explanation:

The said query in SQL that returns information about medications prescribed to patients during their appointments, including the patient's name, the physician's name, and the medication name.

The query performs a join between the 'patient', 'prescribes', 'physician', and 'medication' tables, based on their relational columns.

The 'prescribes' and 'patient' tables are joins based on the patient and ssn columns, the 'prescribes' and 'physician tables are joins based on the physician and employeeid columns, and the 'medication ' and the 'prescribes' and 'medication' tables are joins based on the medication and code columns.

The included WHERE clause filters the results by medications that were prescribed during appointments. This is determined by checking whether the appointment identifier in the 'prescribes' table is not NULL.

Practice Online

E R Diagram of Hospital Database:

Have another way to solve this solution? Contribute your code (and comments) through Disqus.

Previous SQL Exercise: Names of patients, their doctors, and medications.
Next SQL Exercise: Find patients without an appointment.