step1: 查找已签到的相关数据，按用户id进行分组，按签到日期排序后，对其依次编号；

step2: 将日期减去编号后得到dif，按照user_id及dif进行分组，统计个数即为每个用户连续签到的天数；

step3: 查找连续签到天数中的最大值；

step4: 按user_id排序输出。

SELECT t1.user_id, max(t1.max_continuous_days) as max_continuous_days

from(

select t.user_id, date_sub(t.sign_date, interval t.rn day) as dif, count(1) as max_continuous_days

from(

select user_id, sign_date, row_number() over(partition by user_id order by sign_date ) as rn

from user_sign_tb

where if_sign=1)t

group by t.user_id, dif)t1

group by t1.user_id

ORDER by t1.user_id;