CREATE TABLE `study_days` (
  `user_id` text NOT NULL,
  `plan_date` text NOT NULL,
  `durations` text NOT NULL DEFAULT '{}',
  `weekly_review` text NOT NULL DEFAULT '',
  `next_focus` text NOT NULL DEFAULT '',
  `updated_at` text NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY(`user_id`, `plan_date`)
);
CREATE TABLE `mock_exams` (
  `user_id` text NOT NULL,
  `exam_date` text NOT NULL,
  `listening` text NOT NULL DEFAULT '',
  `reading` text NOT NULL DEFAULT '',
  `writing` text NOT NULL DEFAULT '',
  `translation` text NOT NULL DEFAULT '',
  `note` text NOT NULL DEFAULT '',
  `updated_at` text NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY(`user_id`, `exam_date`)
);