subquery and correlated subquery

Author: HannahIgboke

sql-subqueries/subquery-vs-correlated-subquery/correlated subquery.sql

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+SELECT f.name AS faculty_name, COUNT(t.course_id) AS courses_taught, f.position 
+FROM Faculty f 
+INNER JOIN Teaching t ON t.faculty_id = f.id 
+WHERE year = '2023' AND t.semester = 'SPRING' 
+GROUP BY f.id, t.semester, t.year, f.name, f.position 
+HAVING COUNT(t.course_id) = 
+                            (SELECT MAX(semester_course_count) 
+                            FROM 
+                                (SELECT COUNT(t2.course_id) AS semester_course_count 
+                                FROM Teaching t2 
+                                WHERE t2.faculty_id = f.id 
+                                GROUP BY t2.semester, t2.year) AS semester_counts);

sql-subqueries/subquery-vs-correlated-subquery/subquery.sql

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+SELECT s.name AS student_name, s.gpa 
+FROM Student s 
+WHERE s.id IN 
+            (SELECT r.student_id 
+            FROM Registration r 
+            INNER JOIN Course c ON r.course_id = c.id 
+            WHERE c.department_id = 
+                                    (SELECT id 
+                                    FROM Department 
+                                    WHERE name = 'Mathematics'));