Create subqueries-in-FROM-clause.sql

Author: Latsan

sql-subqueries/how-to-use-SELECT-with-multiple-subqueries-to-same-table-in-SQL/subqueries-in-FROM-clause.sql

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+SELECT s.name, exam_counts.course_name, exam_counts.exam_count
+FROM Student s
+JOIN (
+    SELECT e.student_id, c.name AS course_name, COUNT(*) AS exam_count
+    FROM Exam e
+    JOIN Course c ON e.course_id = c.id
+    GROUP BY e.student_id, c.name
+    HAVING COUNT(*) = (
+        SELECT MAX(exam_count)
+        FROM (
+            SELECT student_id, course_id, COUNT(*) AS exam_count
+            FROM Exam
+            GROUP BY student_id, course_id
+        ) max_counts
+        WHERE max_counts.student_id = e.student_id
+    )
+) exam_counts ON s.id = exam_counts.student_id;