player INTEGER NOT NULL REFERENCES players,
songnumber INTEGER NOT NULL,
- song INTEGER NOT NULL REFERENCES songs,
+ song INTEGER REFERENCES songs,
playmode VARCHAR CHECK (playmode IS NULL OR playmode IN ('single','double')),
difficulty VARCHAR CHECK (difficulty IS NULL OR difficulty IN ('beginner','standard','difficult','expert','challenge')),
- chosen BOOLEAN NOT NULL,
- score INTEGER NOT NULL CHECK (score >= 0 AND score <= 10000),
+ chosen BOOLEAN,
+ score INTEGER CHECK (score IS NULL OR (score >= 0 AND score <= 10000)),
FOREIGN KEY (song) REFERENCES songs (song),
FOREIGN KEY (song, playmode, difficulty) REFERENCES songratings (song, playmode, difficulty),