转载：https://www.cnblogs.com/jiaxinwei/p/13936273.html
SQL计算最长登录天数
计算最长登陆天数主要用两个函数：1.窗口函数row_number()over() 2.date_sub()
1.使用row_number()窗口函数
1 select 2 UID, 3 loadtime, 4 row_number()over(partition by UID order by loadtime) sort 5 from 6 user_login
2.使用date_sub()函数
--取每个用户的连续登陆天数
1 select 2 UID, 3 date_sub(loadtime,sort) as date_group, --拿登陆时间和排序相减，如果差值是定值，可以分成一组，说明用户是连续登陆的 4 min(loadtime) as start, 5 max(loadtime) as end , 6 count(1) as continue_days --连续登陆天数 7 from( 8 select 9 UID, 10 loadtime, 11 row_number()over(partition by UID order by loadtime) sort 12 from 13 user_login 14 ) a 15 group by 16 UID, 17 date_sub(loadtime,sort)
3.以UID分组，取max(continue_days)
1 --- 用户最大登陆天数 2 SELECT 3 UID, 4 max(continue_days) as maxday 5 FROM( 6 select 7 UID, 8 date_sub(loadtime,sort) as date_group, 9 min(loadtime) as start, 10 max(loadtime) as end , 11 count(1) as continue_days 12 from( 13 select 14 UID, 15 loadtime, 16 row_number()over(partition by UID order by loadtime) sort 17 from 18 user_login 19 ) a 20 group by 21 UID, 22 date_sub(loadtime,sort) 23 )t1 24 group by UID
