按天分组，create_time是表中的字段

@Query(value = "SELECT DATE_FORMAT( create_time, '%Y-%m-%d' ) date, COUNT( * ) number FROM register_user  where create_time BETWEEN ?1 and ?2 GROUP BY date; ",nativeQuery = true)
List<Map> countDay(String startDay, String endDay);

-- 按年分组

SELECT DATE_FORMAT(create_time, '%Y') AS year, COUNT(*) AS number FROM register_user WHERE create_time BETWEEN ?1 AND ?2 GROUP BY year;

-- 按年-月分组

SELECT DATE_FORMAT(create_time, '%Y-%m') AS year_month, COUNT(*) AS number FROM register_user WHERE create_time BETWEEN ?1 AND ?2 GROUP BY year_month;

-- 注意：按ISO周数分组（假设周一为一周的开始）可能需要不同的逻辑 -- 这里是一个简化的例子，但请注意它可能不完全符合ISO周数的定义

SELECT CONCAT(DATE_FORMAT(create_time, '%Y'), '-W', WEEK(create_time, 1)) AS year_week, COUNT(*) AS number FROM register_user WHERE create_time BETWEEN ?1 AND ?2 GROUP BY YEAR(create_time), WEEK(create_time, 1);