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SQL Exercise: Names of patients, their doctors, and medications

SQL hospital Database: Exercise-19 with Solution

19. From the following tables, write a SQL query to locate the patients' treating physicians and medications. Return Patient name as "Patient", Physician name as "Physician", 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;

Sample Output:

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

Explanation:

The said query in SQL that returns information about medications prescribed to patients by their physicians, 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.

Practice Online


E R Diagram of Hospital Database:

E R Diagram: SQL Hospital Database.

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Previous SQL Exercise: Patients and their physicians who do not need a nurse.
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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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