text: CREATE TABLE IF NOT EXISTS timetable
    ( id INTEGER PRIMARY KEY AUTOINCREMENT
    , title TEXT NOT NULL
    , start_time DATETIME NOT NULL
    , duration INTEGER NOT NULL
    );
  
  CREATE TABLE IF NOT EXISTS seats
    ( id INTEGER PRIMARY KEY AUTOINCREMENT
    , row INTEGER NOT NULL
    , seat INTEGER NOT NULL
    , available BOOLEAN NOT NULL
    , time_slot_id INTEGER REFERENCES timetable(id)
    );
  
  CREATE TABLE IF NOT EXISTS bookings
    ( id INTEGER PRIMARY KEY AUTOINCREMENT
    , seat_id INTEGER REFERENCES seats(id)
    , time_slot_id INTEGER REFERENCES timetable(id)
    , is_preliminary BOOLEAN NOT NULL
    , created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
    , UNIQUE(seat_id, time_slot_id)
    );
  
  INSERT INTO timetable (title, start_time, duration)
  VALUES ('John Wick 3', '2020-05-11 19:11:23', 120);
  
  INSERT INTO seats (row, seat, available, time_slot_id)
  VALUES (1, 3, true, 1);
  INSERT INTO seats (row, seat, available, time_slot_id)
  VALUES (2, 3, true, 1);
  INSERT INTO seats (row, seat, available, time_slot_id)
  VALUES (3, 3, false, 1);
  