CREATE TABLE IF NOT EXISTS attendance (
    id BIGSERIAL PRIMARY KEY NOT NULL,
    user_id BIGINT NOT NULL,
    mission_id BIGINT NOT NULL,
    confirmed_at BIGINT NOT NULL,
    attending BOOL NOT NULL,

    CONSTRAINT fk_user FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE SET NULL,
    CONSTRAINT fk_mission FOREIGN KEY (mission_id) REFERENCES missions(id) ON DELETE CASCADE
);