Composite primary key

[Steven-MKN]

Hi,

I'm just trying to figure out how would one create a composite primary key? i.e I have this SQL as an example and I have no idea what the WatermelonDB implementation of this would be

CREATE TABLE voting (
  QuestionID NUMERIC,
  MemberID NUMERIC,
  PRIMARY KEY (QuestionID, MemberID)
);

Also,
how can I have a custom field as a primary key? i.e

CREATE TABLE station (
  StationCode TEXT PRIMARY KEY
);

This would be ideal as the id is not numeric and there isn't any particular sequence, just unique codes.