从订单信息表(order info)中查询首次下单后第二天仍然下单的用户占所有下单用户的比例，结果保留一位小数使用百分数显示，

SELECT ROUND((COUNT(DISTINCT second_day_users.user_id) / COUNT(DISTINCT first_day_users.user_id)) * 100, 1) AS conversion_rate
FROM (
    SELECT user_id
    FROM `order`
    WHERE DATEDIFF(create_date, (SELECT MIN(create_date) FROM `order`)) = 1
) second_day_users
right JOIN (
    SELECT user_id
    FROM `order`
    WHERE create_date = (SELECT MIN(create_date) FROM `order`)
) first_day_users
ON second_day_users.user_id = first_day_users.user_id;

INSERT INTO `order` ( order_id, user_id, create_date, total_amount ) SELECT
1,
101,
'2021-09-27',
29000.00 UNION ALL
SELECT
 2,
 103,
 '2020-10-02',
 28000.00 UNION ALL
SELECT
 3,
 101,
 '2021-09-28',
 29000.00 UNION ALL
SELECT
 4,
 101,
 '2021-09-30',
 29000.00 UNION ALL
SELECT
 5,
 103,
 '2020-10-03',
 28000.00 UNION ALL
SELECT
 6,
 103,
 '2020-10-04',
 28000.00 UNION ALL
SELECT
 7,
 104,
 '2020-10-02',
 28000.00 UNION ALL
SELECT
 8,
 104,
 '2020-10-02',
 28000.00 UNION ALL
SELECT
 9,
 104,
 '2020-10-03',
 28000.00 UNION ALL
SELECT
 10,
 104,
 '2020-10-04',
 28000.00