CREATE TABLE schedule_entries (
    id         INTEGER PRIMARY KEY AUTOINCREMENT,
    user_id    INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    date       TEXT    NOT NULL UNIQUE,  -- YYYY-MM-DD; one person per day
    created_at INTEGER NOT NULL DEFAULT (strftime('%s', 'now'))
);

CREATE INDEX schedule_entries_date_idx ON schedule_entries(date);