SQL Exercise: Patients who have been prescribed some medication

SQL hospital Database: Exercise-36 with Solution

36. From the following table, write a SQL query to determine which patients have been prescribed medication by their primary care physician. Return Patient name as "Patient", and Physician Name as "Physician".

Sample table: patient

Sample table: prescribes

Sample table: physician

Sample Solution:

SELECT pt.name AS "Ptient",
       p.name AS "Physician"
FROM patient pt
JOIN prescribes pr ON pr.patient=pt.ssn
JOIN physician p ON pt.pcp=p.employeeid
WHERE pt.pcp=pr.physician
  AND pt.pcp=p.employeeid;

Sample Output:

   Ptient   |  Physician
 John Smith | John Dorian
(1 row) 


This SQL query selects the names of patients and their primary care physicians (PCPs), along with the name of the physician who prescribed medication for the patient.

The first JOIN keyword links the 'patient' and 'prescribes' tables based on the patient and SSN columns. The second JOIN links the 'patient' and 'physician' tables based on the pcp and employeeid columns.

The WHERE clause includes two conditions to filter the results. The first condition ensures that the patient's PCP is also the physician who prescribed medication for the patient. The second condition ensures that the PCP employee ID matches the physician employee ID.

Practice Online

E R Diagram of Hospital Database:

E R Diagram: SQL Hospital Database.

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Previous SQL Exercise: Find nurses who have ever been on call for room 122.
Next SQL Exercise: Patients who have had a procedure costing over $5,000.

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SQL: Tips of the Day

Grouped LIMIT in PostgreSQL: Show the first N rows for each group?

db=# SELECT * FROM xxx;
 id | section_id | name
  1 |          1 | A
  2 |          1 | B
  3 |          1 | C
  4 |          1 | D
  5 |          2 | E
  6 |          2 | F
  7 |          3 | G
  8 |          2 | H
(8 rows)

I need the first 2 rows (ordered by name) for each section_id, i.e. a result similar to:

id | section_id | name
  1 |          1 | A
  2 |          1 | B
  5 |          2 | E
  6 |          2 | F
  7 |          3 | G
(5 rows)

PostgreSQL v9.3 you can do a lateral join

select distinct t_outer.section_id, t_top.id, t_top.name from t t_outer
join lateral (
    select * from t t_inner
    where t_inner.section_id = t_outer.section_id
    order by t_inner.name
    limit 2
) t_top on true
order by t_outer.section_id;

Database: PostgreSQL

Ref: https://bit.ly/3AfYwZI


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