CREATE TABLE Students (
    ID INT NOT NULL PRIMARY KEY,
    FirstName nvarchar(50) NOT NULL,
    ClassID INT NOT NULL,
    CONSTRAINT FK_ClassStudents FOREIGN KEY (ClassID) REFERENCES Class(ID)
);
ALTER TABLE Students
    ADD LastName nvarchar(50) NOT NULL;

CREATE TABLE Class (
    ID INT NOT NULL PRIMARY KEY,
    Name nvarchar(10) NOT NULL,
    SchoolID INT NOT NULL,
    CONSTRAINT FK_SchoolClass FOREIGN KEY (SchoolID) REFERENCES School(ID)
);

CREATE TABLE School(
    ID INT NOT NULL PRIMARY KEY,
    Name nvarchar(100)NOT NULL,
    City nvarchar(50) NOT NULL,
    Country nvarchar(50) NOT NULL
);

CREATE TABLE Grades (
    ID INT NOT NULL PRIMARY KEY,
    Student_ID INT NOT NULL,
    VALUE INT NOT NULL,
    Subject nvarchar(20) NOT NULL
    CONSTRAINT FK_StudentsGrades FOREIGN KEY (Student_ID) REFERENCES Students(ID)
);

INSERT INTO School (ID, Name, City, Country)
VALUES (1, 'Liceul Teoretic de Informatica "Grigore Moisil"', 'Iasi', 'Romania')
INSERT INTO School (ID, Name, City, Country)
VALUES (2, 'Colegiul National', 'Iasi', 'Romania')
INSERT INTO School (ID, Name, City, Country)
VALUES (3, 'Colegiul "Costache Negruzzi"', 'Iasi', 'Romania')
INSERT INTO School (ID, Name, City, Country)
VALUES (3, 'Colegiul "Emil Racovita"', 'Iasi', 'Romania')
INSERT INTO School (ID, Name, City, Country)
VALUES (3, 'Liceul "Vasile Alecsandri"', 'Iasi', 'Romania')




INSERT INTO Class (ID, Name, SchoolID)
VALUES (1, '5A', 1)
INSERT INTO Class (ID, Name, SchoolID)
VALUES (2, '5B', 2)
INSERT INTO Class (ID, Name, SchoolID)
VALUES (3, '5C', 1)
INSERT INTO Class (ID, Name, SchoolID)
VALUES (4, '5D', 1)
INSERT INTO Class (ID, Name, SchoolID)
VALUES (5, '5E', 1)

INSERT INTO .Students (ID, FirstName, LastName, ClassID)
VALUES (1, 'Bostan', 'Matei', 1)
INSERT INTO Students (ID, FirstName, LastName, ClassID)
VALUES (2, 'Bostan', 'Luca', 2)

SELECT * FROM Students