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SQL Exercises – Part II

April 20, 2023

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Exercise 1 Consider the following relational database scheme:

Treatment (disease, medication) Doctor(name, disease-of-specialization) Treated (doctor_name, patient_name, date, procedure,

diagnostic) Patients and doctors are uniquely identified by their name A patient may suffer from several diseases, and may take

several medications for each disease. It is possible to a doctor to be a patient and vice-versa. The domains of the attributes "disease" and "disease-of-

specialization" are the same, namely, the set of all diseases. In "treated" relation, the procedure could be consultation, or

intervention (surgery etc.) and the diagnostic could be the name of a disease or the type of intervention.

Write the following queries in SQL:

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Exercise 1 (a) Treatment (disease, medication) Doctor (name, disease-of-specialization) Treated (doctor_name, patient_name, date,

procedure, diagnostic)

Give the name of doctors who don't suffer from any disease.

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Solution 1 (a) – Method 1 Give the name of doctors who don't suffer from any

disease.DoctorsWhoSuffered(name (name=patient_name (Doctor Treated)))name (Doctor) – DoctorsWhoSuffered In SQL:SELECT distinct name FROM DoctorEXCEPTSELECT name FROM Doctor, TreatedWHERE name = patient_name

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Solution 1 (a) – Method 2 Give the name of doctors who don't suffer

from any disease.SELECT distinct d.name FROM DOCTOR d WHERE NOT EXISTS (SELECT * FROM TREATED t WHERE d.name =

t.patient_name);

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Exercise 1 (b) Treatment (disease, medication) Doctor (name, disease-of-specialization) Treated (doctor_name, patient_name, date,

procedure, diagnostic)

List patients who suffer from more than one disease.

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Solution 1 (b) List patients who suffer from more than one disease.Patient1(name1, diagnostic1) (patient_name, diagnostic ( Treated))

Patient2(name2, diagnostic2) (Patient1)

name1 (name1=name2 AND diagnostic1 <> diagnostic2 (Patient1 Patient2)) In SQL:SELECT distinct p1.patient_name FROM TREATED p1, TREATED p2 WHERE p1.patient_name = p2.patient_name AND p1.diagnostic <> p2.diagnostic;

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Exercise 1 (c) Treatment (disease, medication) Doctor (name, disease-of-specialization) Treated (doctor_name, patient_name, date,

procedure, diagnostic)

Give the names of doctors who are also patients suffering from a disease in their own specialization.

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Solution 1 (c) Give the names of doctors who are also patients

suffering from a disease in their own specialization.name (name=patient_name AND disease-of-specialty = diagnostic (Doctor

Treated)) In SQL:SELECT distinct name FROM DOCTOR, TREADTEDWHERE name = patient_name AND disease-of-specialization = diagnostic;

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Exercise 1 (d) Treatment (disease, medication) Doctor (name, disease-of-specialization) Treated (doctor_name, patient_name, date,

procedure, diagnostic)

Find diseases for which there is only one medication.

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Solution 1 (d) – Method 1 Find diseases for which there is only one medication.

DiseaseWithMoreThanOneTreatment (t1.disease (t1.disease=t2.disease

AND t1.medication <> t2.medication (t1(Treatment) t2(Treatment))

disease (Treatment) – DiseaseWithMoreThanOneTreatment

In SQL:SELECT distinct disease FROM TreatmentEXCEPTSELECT t1.disease FROM Treatment t1, Treatment t2WHERE t1.disease =t2.disease AND t1.medication <> t2.medication

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Solution 1 (d) – Method 2 Find diseases for which there is only one medication.

SELECT distinct t1.disease FROM TREATMENT t1WHERE NOT EXISTS (SELECT t2.disease FROM TREATMENT t2 WHERE t1.disease = t2.disease AND t1.medication <>

t2.medication);

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Exercise 1 (e) Treatment (disease, medication) Doctor (name, disease-of-specialization) Treated (doctor_name, patient_name, date,

procedure, diagnostic)

Find the names of patient who had an operation done by a doctor with HIV

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Solution 1 (e) Find the names of patient who had an operation

done by a doctor with HIV.SELECT distinct t1.patient_name FROM TREATED t1 WHERE (t1.procedure=“intervention” AND t1.doctor_name IN ( SELECT distinct d1.name FROM TREATED t2, DOCTOR d1 WHERE (t2.patient_name=d1.name AND t2.diagnostic=“HIV”)));

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Exercise 1 (f) Treatment (disease, medication) Doctor (name, disease-of-specialization) Treated (doctor_name, patient_name, date,

procedure, diagnostic)

List the patients who consulted 2 or more doctors and was given exactly the same diagnosis. List patient’s name, doctor’s name, the date, and the diagnosis.

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Solution 1 (f) List the patients who consulted 2 or more

doctors and was given exactly the same diagnosis. List patient’s name, doctor’s name, the date, and the diagnosis.

SELECT distinct t1.patient_name, t1.doctor_name,

t1.date, t1.diagnostic FROM TREATED t1, TREATED t2 WHERE t1.patient_name = t2.patient_name AND t1.doctor_name <> t2.doctor_name AND t1.diagnostic=t2.diagnostic

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Exercise 2 Consider the following relation scheme about hockey teams:

Team (tname, year, coach, salary) Player (pname, position) Winner (tname, year) Played (pname, tname, year, salary)

Assume that players and coaches appointments with teams are on a calendar year basis.

The team relation indicates teams, their coaches on yearly basis and their salaries.

The player relation indicates players and the position each player plays.

The winner relation indicates the Stanley Cup winners. The played relation indicates players and the team they have

played for on a yearly basis. Write the following queries in SQL:

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Exercise 2 (a) Team (tname, year, coach, salary) Player (pname, position) Winner (tname, year) Played (pname, tname, year, salary)

List all the players who have salary higher than 2M$, and have played for all the teams in the league

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Solution 2 (a) List all the players who have salary

higher than 2M$, and have played for all the teams in the league

SELECT p1.pname FROM PLAYED p1WHERE p1.salary > 20000000Group by p1.pname Having count (distinct p1.tname) = (Select count (distinct team.tname) From TEAM);

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Exercise 2 (b) Team (tname, year, coach, salary) Player (pname, position) Winner (tname, year) Played (pname, tname, year, salary)

List coaches who have also been players, and have coached only teams they once played for.

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Solution 2 (b) List coaches who have also been players, and have

coached only teams they once played for.SELECT distinct t1.coach FROM TEAM t1 EXCEPT SELECT distinct t1.coach FROM TEAM t1 WHERE t1.coach NOT IN (SELECT p1.pname FROM PLAYED p1 WHERE p1.tname=t1.tname);

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Exercise 2 (c) Team (tname, year, coach, salary) Player (pname, position) Winner (tname, year) Played (pname, tname, year, salary)

List all the players who won the Stanley Cup during two consecutive years with two different teams.

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Solution 2 (c) List all the players who won the Stanley Cup during two

consecutive years with two different teams.SELECT distinct a1.pname FROM(SELECT p.pname, p.tname, p.year FROM PLAYED p, WINNER w WHERE p.tname = w.tname AND p.year=w.year;) a1, (SELECT p.pname, p.tname, p.year FROM PLAYED p, WINNER w WHERE p.tname = w.tname AND p.year=w.year;) a2 WHERE a1.pname = a2.pname AND a1.tname <> a2.tname AND (a1.year = a2.year – 1 OR a1.year = a2.year + 1);

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Exercise 2 (d) Team (tname, year, coach, salary) Player (pname, position) Winner (tname, year) Played (pname, tname, year, salary)

List all coaches who earn more than the highest player's salary in the team.

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Solution 2 (d) List all coaches who earn more

than the highest player's salary in the team.Select coach

From Team

Where salary > All (Select salary

From Played

Where Team.tname=Played.tname)