PostgreSQL-Fehler, kein eindeutiger Constraint-Matching gegeben

Question

Der Versuch, eine Datenbank zu erstellen, die es einem Kurs ermöglicht, mehrere Abschnitte zu haben, und einen Abschnitt, mehrere Ereignisse/Perioden zu haben, wenn sie sich treffen. Alles ist richtig verknüpft, aber ich habe ein Problem mit einem PostgreSQL-Fehler, der mir klar macht, dass ich UNIQUE-Attribute in den Tabellen "Sections" und "ClassEvent" benötige, aber ich kann nicht UNIQUE sein, weil es Informationen sind das sollte/kann wiederholt werden.

 

    DROP TABLE IF EXISTS Stats; 
    DROP TABLE IF EXISTS ClassEvent; 
    DROP TABLE IF EXISTS Enrollment; 
    DROP TABLE IF EXISTS DegreeReq; 
    DROP TABLE IF EXISTS DegreeInstance; 
    DROP TABLE IF EXISTS Sections; 
    DROP TABLE IF EXISTS Students; 
    DROP TABLE IF EXISTS Degrees; 
    DROP TABLE IF EXISTS Professors; 
    DROP TABLE IF EXISTS People; 
    DROP TABLE IF EXISTS Courses; 

    -- HOLDS A SPECIFIC COURSE WITHOUT THE INSTANCES OF THE CLASS -- 
    CREATE TABLE Courses (
     courseID  SERIAL  UNIQUE NOT NULL, 
     department VARCHAR(4)   NOT NULL, 
     courseNumber VARCHAR(5)   NOT NULL, 
     courseName TEXT  UNIQUE NOT NULL, 
     credits  INT    NOT NULL, 
     PRIMARY KEY(courseID) 
    ); 

    -- PEOPLE SUPERTYPE -- 
    CREATE TABLE People (
     pid SERIAL   UNIQUE NOT NULL, 
     fname TEXT      NOT NULL, 
     lname TEXT      NOT NULL, 
     PRIMARY KEY(pid) 
    ); 

    -- HOLDS THE DIFFERENT PROFESSORS TEACHING AT THE SCHOOL -- 
    -- SUBTYPE OF PEOPLE -- 
    CREATE TABLE Professors (
     professorID SERIAL UNIQUE NOT NULL, 
     status  TEXT   NOT NULL, 
     CHECK(status = 'Full-Time' OR status = 'Part-time'), 
     PRIMARY KEY(professorID) 
    ); 

    -- HOLDS THE SPECIFIC INSTANCES OF THE CLASS DEPENDING ON THE YEAR AND TERM -- 
    CREATE TABLE Sections (
     crn   INT            UNIQUE NOT NULL, 
     courseID  SERIAL  REFERENCES Courses(courseID)    NOT NULL, 
     year   INT             NOT NULL, 
     term   TEXT             NOT NULL, 
     sectionNumber INT             NOT NULL, 
     startDate  DATE             NOT NULL, 
     endDate  DATE             NOT NULL, 
     professorID INT   REFERENCES Professors(professorID) UNIQUE NOT NULL, 
     PRIMARY KEY(crn, courseID) 
    ); 

    -- HOLDS THE EVENT OF THE CLASS -- 
    -- A CLASS MAY HAVE DIFFERENT DAYS ON WHICH -- 
    -- THEY MEET ON, SO THIS ALLOWS A CERTAIN -- 
    -- SECTION TO HAVE SEVERAL DAYS WITHOUT CONFLICT -- 
    CREATE TABLE ClassEvent (
     crn   INT REFERENCES Sections(crn)     NOT NULL, 
     year  INT REFERENCES Sections(year)     NOT NULL, 
     term  TEXT REFERENCES Sections(term)     NOT NULL, 
     professorID INT REFERENCES Professors(professorID)  NOT NULL, 
     day   TEXT, 
     startTime TIME, 
     endTime  TIME, 
     location TEXT, 
     campus  TEXT, 
     CHECK(day = 'Monday' OR day = 'Tuesday' OR day = 'Wednesday' OR day = 'Thursday' OR day = 'Friday' OR day = 'Saturday' OR day = 'Sunday' OR day = NULL), 
     PRIMARY KEY(crn, year, term) 
    ); 

    -- HOLDS THE STUDENTS THAT WILL BE TAKING THE CLASSES -- 
    -- SUBTYPE OF PEOPLE -- 
    CREATE TABLE Students (
     studentID INT REFERENCES People(pid) UNIQUE NOT NULL, 
     studentName TEXT        NOT NULL, 
     gradYear DATE      UNIQUE NOT NULL, 
     PRIMARY KEY(studentID) 
    ); 


    -- HOLDS A CLASS RECORD FOR STUDENTS (AND POSSIBLY PROFESSORS) -- 
    CREATE TABLE Enrollment (
     studentID INT REFERENCES Students(studentID) UNIQUE NOT NULL, 
     crn  INT REFERENCES Sections(crn)    NOT NULL, 
     grade  TEXT          NOT NULL, 
     PRIMARY KEY(studentID, crn) 
    ); 

    -- HOLDS THE DIFFERENT DEGREES THAT CAN BE ATTAINED AT THE COLLEGE/UNIVERSITY -- 
    CREATE TABLE Degrees (
     degreeID  SERIAL  UNIQUE NOT NULL, 
     degreeName TEXT    NOT NULL, 
     degreeType TEXT    NOT NULL, 
     degDepartment VARCHAR(4)   NOT NULL, 
     CHECK(degreeType = 'Major' OR degreeType = 'Minor' OR degreeType = 'Masters'), 
     PRIMARY KEY(degreeID) 
    ); 

    -- HOLDS THE CLASSES THAT WILL MAKE UP A DEGREE -- 
    CREATE TABLE DegreeReq (
     degreeID INT REFERENCES Degrees(degreeID) UNIQUE NOT NULL, 
     courseID INT REFERENCES Courses(courseID) UNIQUE NOT NULL, 
     PRIMARY KEY(degreeID, courseID) 
    ); 

    -- HOLDS THE INSTANCE OF A DEGREE FOR A CERTAIN STUDENT -- 
    -- FOR EXAMPLE: A STUDENT CAN HAVE A MAJOR AND A MINOR -- 
    -- SO HE/SHE CAN STORE THEM SEPARATELY -- 
    CREATE TABLE DegreeInstance (
     degreeID  INT REFERENCES Degrees(degreeID) UNIQUE NOT NULL, 
     studentID  INT REFERENCES Students(studentID) UNIQUE NOT NULL, 
     startDate  DATE          NOT NULL, 
     endDate   DATE          NOT NULL, 
     creditsRequired INT          NOT NULL, 
     PRIMARY KEY(degreeID, studentID) 
    ); 

    -- HOLDS ALL THE RATE MY PROFESSOR STATS -- 
    CREATE TABLE Stats (
     professorID INT  REFERENCES Professors(professorID) UNIQUE NOT NULL, 
     dateSubmitted TIMESTAMP         UNIQUE NOT NULL, 
     rating  FLOAT            NOT NULL, 
     helpfulness FLOAT            NOT NULL, 
     clarity  FLOAT            NOT NULL, 
     easiness  FLOAT            NOT NULL, 
     PRIMARY KEY(professorID, dateSubmitted) 
    ); 

    INSERT INTO Courses(department, courseNumber, courseName, credits) 
    VALUES 
    ('CMPT', '120L', 'Intro to Programming', 4), 
    ('CMPT', '220L', 'Software Development I', 4), 
    ('CMPT', '221L', 'Software Development II', 4), 
    ('CMPT', '230L', 'Software Systems + Analysis', 4), 
    ('CMPT', '306N', 'Data Communications', 4), 
    ('CMPT', '308L', 'Database Management', 4), 
    ('CMPT', '307N', 'Internetworking', 4), 
    ('CMPT', '330L', 'System Design', 4), 
    ('CMPT', '422L', 'Computer Organization and Architecture', 4), 
    ('CMPT', '435L', 'Algorithm Analysis and Design', 4), 
    ('CMPT', '424L', 'Operating Systems', 4), 
    ('CMPT', '432L', 'Design of Compilers', 4), 
    ('CMPT', '331L', 'Theory of Programming Languages', 4), 
    ('CMPT', '440L', 'Formal Languages and Computability', 4), 
    ('CMPT', '333L', 'Language Study', 4), 
    ('CMPT', '475L', 'CS Project I', 4), 
    ('CMPT', '476L', 'CS Project II', 4), 
    ('BUS', '100N', 'Intro to Business & Management', 4), 
    ('MATH', '130L', 'Intro to Statistics I', 3), 
    ('MATH', '241L', 'Calculus I', 4), 
    ('MATH', '242L', 'Calculus II', 4), 
    ('FYS', '101L', 'First Year Seminar', 4), 
    ('ENG', '120L', 'Writing for College', 3), 
    ('PHIL', '101L', 'Philosophical Perspectives', 3), 
    ('MUS', '120L', 'Theory of Music I', 3), 
    ('ECON', '103L', 'Principles of Microeconomics', 3), 
    ('ECON', '104L', 'Principles of Macroeconomics', 3), 
    ('MATH', '343L', 'Calculus III', 4), 
    ('MATH', '310L', 'Intro to Mathematics Reasoning', 3), 
    ('CMPT', '416N', 'Intro to Cybersecurity', 4), 
    ('CMPT', '446N', 'Computer Graphics', 4), 
    ('CMPT', '404L', 'Artificial Intelligence', 4), 
    ('CMPT', '305L', 'Technology, Ethics and Society', 3), 
    ('CMPT', '192N', 'Competitive Programming', 1); 

    INSERT INTO People(fname, lname) 
    VALUES 
    ('Marcos', 'Barbieri'), 
    ('James', 'Crowley'), 
    ('Kaylee', 'Pope'), 
    ('Pablo', 'Rivas'), 
    ('Matthew', 'Johnson'), 
    ('Anne', 'Matheus'), 
    ('Joe', 'Smith'), 
    ('Mike', 'Emmet'), 
    ('Michael', 'Jordan'), 
    ('Alan', 'Labouseur'); 

    INSERT INTO Professors(professorID, status) 
    VALUES 
    (4, 'Full-Time'), 
    (5, 'Full-Time'), 
    (6, 'Full-Time'), 
    (7, 'Full-Time'), 
    (10, 'Full-Time'); 

    INSERT INTO Sections(crn, courseID, year, term, sectionNumber, startDate, endDate, professorID) 
    VALUES 
    (11111, 1, 2016, 'Fall', 111, '2016-08-29', '2016-12-15', 4), 
    (11112, 1, 2016, 'Fall', 112, '2016-08-29', '2016-12-15', 4), 
    (11113, 1, 2016, 'Fall', 113, '2016-08-29', '2016-12-15', 4), 
    (11121, 2, 2016, 'Fall', 111, '2016-08-29', '2016-12-15', 5), 
    (11122, 2, 2016, 'Fall', 112, '2016-08-29', '2016-12-15', 5), 
    (11123, 2, 2016, 'Fall', 113, '2016-08-29', '2016-12-15', 5), 
    (11211, 3, 2016, 'Fall', 111, '2016-08-29', '2016-12-15', 6), 
    (11212, 3, 2016, 'Fall', 112, '2016-08-29', '2016-12-15', 6), 
    (11213, 3, 2016, 'Fall', 113, '2016-08-29', '2016-12-15', 6), 
    (11214, 4, 2016, 'Fall', 111, '2016-08-29', '2016-12-15', 7), 
    (11215, 4, 2016, 'Fall', 112, '2016-08-29', '2016-12-15', 7), 
    (11216, 5, 2016, 'Fall', 111, '2016-08-29', '2016-12-15', 10), 
    (11217, 6, 2016, 'Fall', 111, '2016-08-29', '2016-12-15', 10), 
    (11118, 6, 2016, 'Fall', 112, '2016-08-29', '2016-12-15', 4), 
    (11119, 6, 2016, 'Fall', 113, '2016-08-29', '2016-12-15', 5), 
    (11120, 6, 2016, 'Fall', 114, '2016-08-29', '2016-12-15', 4), 
    (11200, 7, 2016, 'Fall', 111, '2016-08-29', '2016-12-15', 5), 
    (11201, 7, 2016, 'Fall', 112, '2016-08-29', '2016-12-15', 5), 
    (11202, 8, 2016, 'Fall', 111, '2016-08-29', '2016-12-15', 10), 
    (11203, 9, 2016, 'Fall', 111, '2016-08-29', '2016-12-15', 10), 
    (11204, 10, 2016, 'Fall', 111, '2016-08-29', '2016-12-15', 6), 
    (11205, 10, 2016, 'Fall', 112, '2016-08-29', '2016-12-15', 6), 
    (11206, 10, 2016, 'Fall', 113, '2016-08-29', '2016-12-15', 6), 
    (11207, 10, 2016, 'Fall', 114, '2016-08-29', '2016-12-15', 6), 
    (11208, 11, 2016, 'Fall', 111, '2016-08-29', '2016-12-15', 4), 
    (11209, 11, 2016, 'Fall', 112, '2016-08-29', '2016-12-15', 4), 
    (11222, 12, 2016, 'Fall', 111, '2016-08-29', '2016-12-15', 4), 
    (11333, 12, 2016, 'Fall', 112, '2016-08-29', '2016-12-15', 5), 
    (11445, 12, 2016, 'Fall', 113, '2016-08-29', '2016-12-15', 7), 
    (11111, 12, 2016, 'Fall', 111, '2016-08-29', '2016-12-15', 4), 
    (11678, 13, 2016, 'Fall', 111, '2016-08-29', '2016-12-15', 10), 
    (11679, 13, 2016, 'Fall', 112, '2016-08-29', '2016-12-15', 4); 

    SELECT * FROM Sections; 

Ich versuche, dies zu tun, und ich erhalte den folgenden Fehler:

ERROR: there is no unique constraint matching given keys for referenced table "sections" 
********** Error ********** 

ERROR: there is no unique constraint matching given keys for referenced table "sections" 
SQL state: 42830

Answer 1

Sie nicht Jahr und Begriff als Fremdschlüssel in der Klasse Ereignistabelle haben müssen. Diese Information ist redundant, da sie in der Sektionstabelle über die CRN nachgeschlagen werden kann. Ich schlage vor, wenn Sie Ihre Aussage für ClassEvents wie folgt erstellen:

CREATE TABLE ClassEvent (
    crn   INT REFERENCES Sections(crn)     NOT NULL,   
    professorID INT REFERENCES Professors(professorID)  NOT NULL, 
    day   TEXT NOT NULL, 
    startTime TIME NOT NULL, 
    endTime  TIME, 
    location TEXT, 
    campus  TEXT, 
    CHECK(day = 'Monday' OR day = 'Tuesday' OR day = 'Wednesday' OR day = 'Thursday' OR day = 'Friday' OR day = 'Saturday' OR day = 'Sunday' OR day = NULL), 
    PRIMARY KEY(crn, day, startTime,professorID) 
); 

I Primärschlüssel geändert habe eine Kombination natürlich, Datum/Uhrzeit und Professor zu sein - wie ein Professor kann nicht an einem bestimmten Punkt mehr als Kurs unterrichtet in Zeit.