title: ORA-02256: el número de columnas de referencia debe coincidir con las columnas de referencias (este es el error que me devuelve)
body: <pre><code>create table Vaixell (
  
    Id_Vaixell varchar(20) not null,
  
    Cabines numeric not null,
  
    Restaurants numeric not null,
  
    N_persones numeric not null,
  
    PRIMARY KEY(Id_Vaixell)
  
  );
  
  create table Clients (
  
    Id_client varchar(20) not null,
  
    Id_billet varchar(20) not null,
  
    DNI varchar(20) not null,
  
    PRIMARY KEY(DNI,Id_billet,Id_client)
  
  );
  
  create table Cabina (
  
    Id_cabina varchar(20) not null,
  
    PRIMARY KEY (Id_cabina)
  
  );
  
  create table tipus_cabina (
  
   Id_tipus varchar(20) not null,
  
   Capacitat numeric not null,
  
   PRIMARY KEY (Id_tipus)
  
  );
  
  create table Botigues (
  
   Id_botiga varchar(20) not null,
  
   Nom_botiga char(10) not null,
  
   PRIMARY KEY(Id_botiga)
  
  );
  
  create table Tipus_botiga (
  
   tipo_botiga varchar(20) not null,
  
   PRIMARY KEY (tipo_botiga)
  
  );
  
  create table Rutes (
  
   Id_epoca varchar(20) not null,
  
   Id_ruta varchar(20) not null,
  
   PRIMARY KEY (Id_ruta)
  
  );
  
  create table Treballadors (
  
    DNI varchar(20) not null ,
  
    Id_treballador varchar(20) not null,
  
    Lloc_treball varchar(20) not null,
  
    Dia date not null,
  
    Hora TIMESTAMP not null,
  
    Nom char(10) not null,
  
    PRIMARY KEY(Id_treballador)
  
  );
  
  create table Restaurants(
  
   Id_restaurant varchar(20) not null,
  
   Id_menu varchar(20) not null,
  
   Id_reserva varchar(20) not null,
  
   Tipus varchar(20) not null,
  
   Preu numeric not null,
  
   PRIMARY KEY (Id_restaurant,Id_reserva,Id_menu)
  
  );
  
  create table Reserva (
  
    Id_reserva varchar(20) not null,
  
    Id_client varchar(20) not null,
  
    Id_billet varchar(20) not null,
  
    DNI varchar(20) not null,
  
    Id_ruta varchar(20) not null,
  
    Id_cabina varchar(20) not null,
  
    Preus int not null,
  
    Data_ date not null,
  
    PRIMARY KEY (Id_reserva,Id_billet,Id_ruta,Id_cabina,DNI,Id_client),
  
    CONSTRAINT clients_a_reserva_fk
  
      FOREIGN KEY (Id_billet,DNI,Id_client)
  
      references Clients (Id_billet,DNI,Id_client),
  
    CONSTRAINT rutes_a_reserva_fk
  
      FOREIGN KEY (Id_ruta)
  
      references Rutes (Id_ruta),
  
    CONSTRAINT cabina_a_reserva_fk
  
      FOREIGN KEY (Id_cabina)
  
      references Cabina (Id_cabina)
  
  );
  
  create table Excursions (
  
    Edat_minima numeric not null,
  
    Id_reserva varchar(20) not null,
  
    Descripcio varchar(100) not null,
  
    Opcional varchar(30) null,
  
    PRIMARY KEY(Edat_minima,Id_reserva),
  
    CONSTRAINT reserva_a_excursions_fk
  
      FOREIGN KEY (Id_reserva)
  
      references Reserva (Id_reserva)
  
  );
  
  create table Activitats (
  
    tipus_activitat varchar(20) not null,
  
    Id_reserva varchar(20) not null,
  
    PRIMARY KEY (tipus_activitat,Id_reserva),
  
     CONSTRAINT reserva_a_activitats_fk
  
      FOREIGN KEY (Id_reserva)
  
      references Reserva (Id_reserva)
  
  );
  
  create table Incidencies (
  
    Id_treballador varchar(20) not null,
  
    N_incidencia varchar(20) not null,
  
    Dia date not null,
  
    Hora TIMESTAMP not null,
  
    Comentari varchar(100) null,
  
    PRIMARY KEY(N_incidencia),
  
    CONSTRAINT Incidencies_a_treballador_fk
  
      FOREIGN KEY (Id_treballador)
  
      references Treballadors (Id_treballador)
  
  );
  
  create table Port_desti (
  
   N_port numeric(20) not null,
  
   Id_ruta varchar(20) not null,
  
   Ciutat_atracament varchar(20) not null,
  
   PRIMARY KEY (N_port,Id_ruta),
  
   CONSTRAINT ruta_a_port_fk
  
      FOREIGN KEY (Id_ruta)
  
      references Rutes (Id_ruta)
  
  );
  
  create table reserves_restaurant(
  
   Id_reserva varchar(20) not null,
  
   Id_menu varchar(20) not null,
  
   PRIMARY KEY (Id_reserva,Id_menu),
  
    CONSTRAINT Restaurants_a_reserves_fk
  
      FOREIGN KEY (Id_reserva,Id_menu)
  
      references Restaurants(Id_reserva,Id_menu)
  
  );
  
  create table client_a_reserva(
  
   Id_client varchar(20) not null,
  
   Id_restaurant varchar(20) not null,
  
   PRIMARY KEY (Id_client, Id_restaurant),
  
   CONSTRAINT clients_a_rerserva_fk
  
      FOREIGN KEY (Id_client)
  
      references Clients (Id_client),
  
   CONSTRAINT Restaurant_a_clients_fk
  
      FOREIGN KEY (Id_restaurant)
  
      references Restaurants (Id_restaurant)
  
  );
  </code></pre>