SQL Exercise: Find all physicians who completed a medical procedure

SQL hospital Database: Exercise-33 with Solution

33. From the following table, write a SQL query to find all physicians who completed a medical procedure with certification after the expiration date of their license. Return Physician Name as "Physician", Position as "Position".

Sample table: physician

Sample table: undergoes

Sample table: trained_in

Sample Solution:

SELECT name AS "Physician",
       position AS "Position"
FROM physician
WHERE employeeid IN
    ( SELECT physician
     FROM undergoes u
     WHERE date >
         ( SELECT certificationexpires
          FROM trained_in t
          WHERE t.physician = u.physician
            AND t.treatment = u.procedure ) );

Sample Output:

  Physician   |           Position
 Todd Quinlan | Surgical Attending Physician
(1 row)


This SQL query retrieves the names and positions of physicians whose certification has expired for a procedure they have performed.

The WHERE clause filters the results where the "employeeid" column is found in a subquery.

The WHERE clause of the subquery include only those records where the "date" column is greater than the certification expiration date for the procedure.

The certification expiration date is obtained from inner most subquery which selects the "certificationexpires" column from the 'trained_in' table where the physician and procedure match those in the outer subquery.

Practice Online

E R Diagram of Hospital Database:

E R Diagram: SQL Hospital Database.

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Previous SQL Exercise: Doctors do the same procedure but are not certified.
Next SQL Exercise: Medical procedures done after certification expired.

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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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