MYSQL - RELATIONS

    // 
FOREIGN KEY REFERENCES Provincia(Id)

    

    // 1 A 1  / ONE TO ONE
    CREATE TABLE Country(
    Pk_Country_Id INT IDENTITY PRIMARY KEY,
    Name VARCHAR(100),
    Officiallang VARCHAR(100),
    Size INT(11),);

    CREATE TABLE UNrepresentative(
    Pk_UNrepresentative_Id INT PRIMARY KEY,
    Name VARCHAR(100),
    Gender VARCHAR(100),
    Fk_Country_Id INT UNIQUE FOREIGN KEY REFERENCES Country(Pk_Country_Id));

    

    // 1 A MUCHOS / ONE TO MANY
    CREATE TABLE  Modelo(
    IdModelo int primary key,
    Nombre varchar(30) )
    go
    CREATE TABLE helicoptero (
    Matricula varchar(12) primary key,
    IdModelo int foreign key references modelo ( idModelo) )  
    go

    //OTHER EXAMPLE
    CREATE TABLE Car(
    Pk_Car_Id INT PRIMARY KEY,
    Brand VARCHAR(100),
    Model VARCHAR(100));
    //ONE TO MANY
    CREATE TABLE Engineer(
    Pk_Engineer_Id INT PRIMARY KEY,
    FullName VARCHAR(100),
    MobileNo CHAR(11),
    Fk_Car_Id INT FOREIGN KEY REFERENCES Car(Pk_Car_Id));
    

    // MUCHOS A MUCHOS / MANY TO MANY

    CREATE TABLE pasajero( idPasajero varchar(15) primary key,
    Nombre varchar(30),
    Apellidos varchar(40),
    Peso int default 80)

    CREATE TABLE  Billete -- relacion vuelo pasajero.(
    matricula varchar(12), 
    fecha datetime ,
    foreign key (matricula,fecha) references vuelo (matricula,fecha),
    idPasajero varchar(15) foreign key references pasajero (idPasajero),
    primary key (matricula,fecha,idPasajero) )


    //OTHER EXAMPLE
    CREATE TABLE Student(
    StudentID INT(10) PRIMARY KEY,
    Name VARCHAR(100),);
    CREATE TABLE Class(
    ClassID INT(10) PRIMARY KEY,
    Course VARCHAR(100),);
    //MANY TO MANY 
    CREATE TABLE StudentClassRelation(
    StudentID INT(15) NOT NULL,
    ClassID INT(14) NOT NULL,
    FOREIGN KEY (StudentID) REFERENCES Student(StudentID),
    FOREIGN KEY (ClassID) REFERENCES Class(ClassID),
    UNIQUE (StudentID, ClassID));