前述
sql 中 between 的边界问题 ---- between 边界：闭区间，not between 边界：开区间
在 sql 中，
- between 边界：闭区间
- not between 边界：开区间
题目描述
leetcode题目：1890. 2020年最后一次登录
Code
写法一：简单写法
过滤2020年后，再选最大值。
select user_id, max(time_stamp) as last_stamp
from Logins
where year(time_stamp) = '2020'
group by user_id
写法二：窗口函数
select user_id, time_stamp as last_stamp
from(
select *,
row_number() over(partition by user_id order by time_stamp desc) as rk
from Logins
where time_stamp between '2020-01-01 00:00:00' and '2020-12-31 23:59:59'
-- where year(time_stamp) = '2020'
) A
where rk = 1
where time_stamp between '2020-01-01 00:00:00' and '2020-12-31 23:59:59' 和
where year(time_stamp) = '2020' 两种写法都可以。
注意：
在 sql 中，
- between 边界：闭区间
- not between 边界：开区间
