text: DROP TABLE IF EXISTS users CASCADE;
  
  CREATE TABLE users (
      id SERIAL PRIMARY KEY,
      username TEXT NOT NULL,
      password TEXT NOT NULL
  );
  
  DROP TABLE IF EXISTS shops CASCADE;
  
  CREATE TABLE IF NOT EXISTS shops (
      id SERIAL PRIMARY KEY,
      owner_id integer REFERENCES users (id) NOT NULL,
      address TEXT NOT NULL,
      postcode TEXT NOT NULL,
      name TEXT NOT NULL
  );
  
  DROP TABLE IF EXISTS shop_items CASCADE;
  
  CREATE TABLE IF NOT EXISTS shop_items (
      id SERIAL PRIMARY KEY,
      shop_id integer REFERENCES shops (id) NOT NULL
  );
  
  