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Semester 1/Database Systems/Assignment/Querying Database.md

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+3. List the names of patients who are at least fifty years old. Your query should always generate a list in which the names are sorted in alphabetical order. The ordering must not depend upon the order in which you entered data into your database.
+
+```SQL
+SELECT patient_name
+FROM patient
+WHERE age >= 50
+ORDER BY patient_name;
+```
+
+![](Pasted%20image%2020231204184010.png)
+
+4. List the name of each type of organ, together with the total number of donations of that type of organ.
+
+```SQL
+SELECT organ_type, COUNT( organ_type )
+FROM organ
+INNER JOIN operation ON operation.organ_id = organ.organ_id
+GROUP BY organ_type;
+```
+
+![](Pasted%20image%2020231204184814.png)
+
+5. List the identifiers of hospitals where a transplant has been performed, together with the number of transplant operations at the hospital.
+
+```SQL
+SELECT hospital_id, COUNT( hospital_id )
+FROM transplant_unit
+INNER JOIN operation ON transplant_unit.unit_id = operation.unit_id
+GROUP BY hospital_id;
+```
+
+![](Pasted%20image%2020231204191255.png)
+
+6. Output the age of the oldest person who has donated in a hospital in Manchester.
+
+```SQL
+SELECT age
+FROM donor
+WHERE donor_id IN (
+	SELECT donor_id
+	FROM operation
+	WHERE unit_id IN (
+		SELECT unit_id
+		FROM transplant_unit
+		WHERE hospital_id IN (
+			SELECT hospital_id
+			FROM hospital
+			WHERE city LIKE '%Manchester%'
+		)
+	)
+);
+```