title: No matching unique or primary key for this column-list (Trying to add two FK's )
body: <p>I'm getting the error no matching unique or primary key for this column list, what could be? I'm using oracle live sql. The table who is getting the error is the last one, the others are working ok. The error is ORA 02270</p>
  <pre><code>CREATE TABLE flightBooking
  ( bookingCode varchar(5) not null, 
    stretchSet varchar(50),
    expireDate varchar(12),
    CONSTRAINT flightBooking_pk PRIMARY KEY (bookingCode)
  ); 
  
  CREATE TABLE customer
  ( cpf varchar(10),
    rg varchar(7),
    personName varchar(30),
    birth varchar(12),
    email varchar(30),
    city varchar(30),
    uf varchar(2),
    bookingCode varchar(5) not null,
    CONSTRAINT fk_bookingCode FOREIGN KEY (bookingCode) REFERENCES flightBooking(bookingCode)
  );  
  
  CREATE TABLE stretch
  ( flightDate varchar(12),
    flightHour varchar(6),
    flightClass varchar(15),
    flightCode varchar(5) not null,
    destination varchar(30),
    origin varchar(30),
    scale varchar(60),
    aeroplaneType varchar(30)
  );
  
  CREATE TABLE sell
  (voucher varchar(50),
   bookingCode varchar(5) not null,
   flightCode varchar(5) not null,
   CONSTRAINT fk_bookingCode FOREIGN KEY (bookingCode) REFERENCES flightBooking(bookingCode),
   CONSTRAINT fk_flightCode FOREIGN KEY (flightCode) REFERENCES stretch(flightCode)
  
  );````
  </code></pre>