lab-mysql-erasmus Lucia

my_code.sql

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+USE erasmus;
+
+-- 1
+SELECT Grade_Category, FLOOR(AVG(age)) FROM 
+(SELECT grades.student_id, TIMESTAMPDIFF(YEAR,dob,CURDATE()) AS age, 
+		CASE
+			WHEN grades>8 THEN "EXCELLENT"
+            WHEN grades<9 AND grades>6 THEN "GOOD"
+            WHEN grades<7 AND grades>4 THEN "PASS"
+            ELSE "FAIL"
+        END AS Grade_Category
+FROM grades JOIN students ON grades.student_id = students.student_id) as tab
+GROUP BY Grade_Category;
+
+
+-- 2
+SELECT University_name, FLOOR(AVG(age)) AS average_age FROM
+(SELECT uni_name AS University_name, (TIMESTAMPDIFF(YEAR,dob,CURDATE())) AS age
+FROM university JOIN campus ON university.university_id = campus.university_id
+				JOIN students ON campus.campus_id = students.campus_id) as tab
+GROUP BY University_name
+ORDER BY average_age DESC;
+
+
+-- 3
+SELECT subj_name, students_failed, total_students, (students_failed * 100 / total_students) as proportion_failed
+FROM ( SELECT subjects.subj_name,
+			   SUM(CASE WHEN grades.grades < 5 THEN 1 ELSE 0 END) AS students_failed,
+			  COUNT(*) AS total_students
+FROM students
+	JOIN grades ON students.student_id = grades.student_id
+	JOIN subjects ON grades.subject_id = subjects.subject_id
+GROUP BY subjects.subj_name) as tab
+GROUP BY subj_name
+ORDER BY proportion_failed DESC;
+
+
+-- 4
+SELECT CASE
+			WHEN erasmus.agreement_code IS NOT NULL THEN 'w_erasmus' ELSE 'wo_erasmus'
+	   END AS erasmus_status,
+	   AVG(grades.grades) AS average_grade
+FROM students LEFT JOIN international_agreement ON students.student_id = international_agreement.student_id
+			  JOIN grades ON students.student_id = grades.student_id
+GROUP BY erasmus_status;
+
+
+-- 5
+SELECT * FROM bachelor;
+
+SELECT university.university_id, university.uni_name,
+    COUNT(CASE WHEN bachelor.bachelor_id LIKE 'b%' THEN bachelor.bachelor_id END) AS bachelor_count,
+    COUNT(CASE WHEN bachelor.bachelor_id LIKE 'M%' THEN bachelor.bachelor_id END) AS master_count,
+    COUNT(CASE WHEN bachelor.bachelor_id LIKE 'D%' THEN bachelor.bachelor_id END) AS phd_count
+FROM university
+LEFT JOIN bachelor ON university.university_id = bachelor.university_id
+GROUP BY university.university_id, university.uni_name;
+
+SELECT 'B001' LIKE 'm%'
+
+
+
+
+