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1DROP DATABASE IF EXISTS school;
2CREATE DATABASE school CHARSET 'utf8';
3USE school;
4
5CREATE TABLE Students(
6	Id INTEGER NOT NULL AUTO_INCREMENT PRIMARY KEY,
7	Name VARCHAR(150) NOT NULL,
8	Num INTEGER NOT NULL,
9	ClassNum INTEGER NOT NULL,
10	ClassLetter CHAR(1) NOT NULL,
11	Birthday DATE,
12	EGN CHAR(10),
13	EntranceExamResult NUMERIC(3,2)
14);
15
16CREATE TABLE Subjects(
17	Id INTEGER NOT NULL AUTO_INCREMENT,
18	Name VARCHAR(100),
19	
20	PRIMARY KEY(Id)
21);
22
23CREATE TABLE StudentMarks(
24	StudentId INTEGER NOT NULL,
25	SubjectId INTEGER NOT NULL,
26	ExamDate DATETIME NOT NULL,
27	Mark NUMERIC(3,2) NOT NULL,
28	
29	PRIMARY KEY( StudentId, SubjectId, ExamDate ),
30	FOREIGN KEY (StudentId) REFERENCES Students(Id),
31	FOREIGN KEY (SubjectId) REFERENCES Subjects(Id)
32);
33
34CREATE TABLE MarkWords(
35	RangeStart NUMERIC(3,2) NOT NULL,
36	RangeEnd NUMERIC(3,2) NOT NULL,
37	MarkAsWord VARCHAR(15),
38	
39	PRIMARY KEY(RangeStart, RangeEnd)
40);
41
42INSERT INTO Students(Id, Name, Num, ClassNum, ClassLetter, Birthday, EGN) VALUES( 101, 'Зюмбюл Петров', 10, 11, 'а', '1999-02-28', NULL );
43INSERT INTO Students(Name, Num, ClassNum, ClassLetter, Birthday, EGN) VALUES( 'Исидор Иванов', 15, 10, 'б', '2000-02-29', '0042294120' );
44INSERT INTO Students(Name, Num, ClassNum, ClassLetter, Birthday, EGN) VALUES( 'Панчо Лалов', 20, 10, 'б', '2000-05-01', NULL );
45INSERT INTO Students(Name, Num, ClassNum, ClassLetter, Birthday, EGN) VALUES( 'Петраки Ганьов', 20, 10, 'а', '1999-12-25', '9912256301' );
46INSERT INTO Students(Name, Num, ClassNum, ClassLetter, Birthday, EGN) VALUES( 'Александър Момчев', 1, 8, 'а', '2002-06-11', NULL );
47
48INSERT INTO Subjects(Id, Name) VALUES( 11, 'Английски език' );
49INSERT INTO Subjects(Name) VALUES( 'Литература' );
50INSERT INTO Subjects(Name) VALUES( 'Математика' );
51INSERT INTO Subjects(Name) VALUES( 'СУБД' );
52
53INSERT INTO StudentMarks VALUES( 101, 11, '2017-03-03', 6 );
54INSERT INTO StudentMarks VALUES( 101, 11, '2017-03-31', 5.50 );
55INSERT INTO StudentMarks VALUES( 102, 11, '2017-04-28', 5 );
56INSERT INTO StudentMarks VALUES( 103, 12, '2017-04-28', 4 );
57INSERT INTO StudentMarks VALUES( 104, 13, '2017-03-03', 5 );
58INSERT INTO StudentMarks VALUES( 104, 13, '2017-04-07', 6 );
59INSERT INTO StudentMarks VALUES( 104, 11, '2017-04-07', 4.50 );
60
61INSERT INTO MarkWords VALUES( 2, 2.50, 'Слаб' );
62INSERT INTO MarkWords VALUES( 2.50, 3.50, 'Среден' );
63INSERT INTO MarkWords VALUES( 3.50, 4.50, 'Добър' );
64INSERT INTO MarkWords VALUES( 4.50, 5.50, 'Мн. добър' );
65INSERT INTO MarkWords VALUES( 5.50, 6, 'Отличен' );
66
67SELECT sub.Name, COUNT(sm.Mark)
68FROM Subjects sub
69LEFT JOIN StudentMarks sm on sm.SubjectId = sub.Id and sm.Mark = 6
70GROUP BY sub.Id;
71
72SELECT s.Name, sub.Name, AVG(sm.Mark)
73FROM Students s
74JOIN Subjects sub
75LEFT JOIN StudentMarks sm ON sm.SubjectId = sub.Id AND sm.StudentId = s.Id
76GROUP BY s.Id, sub.Name; 
77
78SELECT s.Name, AVG(sm.Mark) as averageMark
79FROM Students s
80JOIN StudentMarks sm ON sm.StudentId = s.Id
81GROUP BY s.Name
82HAVING averageMark >= 5.50;
83
84SELECT s.Name
85FROM Subjects s
86LEFT JOIN StudentMarks sm ON sm.SubjectId = s.Id
87WHERE sm.Mark IS null;
88
89Select s.Name, sm.Mark
90from Students s
91JOIN StudentMarks sm ON s.Id = sm.StudentId;
92
93Select s.Name, s.ClassNum, s.ClassLetter
94from Students s
95Order By s.ClassNum, s.ClassLetter, s.Name;
96
97Select sub.Name, AVG(sm.Mark) as average
98FROM Subjects sub
99JOIN StudentMarks sm ON sm.SubjectId = sub.Id
100GROUP BY sub.Name
101HAVING average < 3.00
102ORDER BY average DESC;
103
104CREATE UNIQUE INDEX unique_student ON Students(Num, ClassNum, ClassLetter);