How to count users from last 7, 15, 30 dyas ago (from sysdate) Oracle SQL

Question

So, I am trying to count my users who login 7,15, & 30 days ago from sysdate. I know I can count users who loged in 7 days ago and I can group them, but I would like to count users who loged in 7, 15, & 30 days ago.

select roel, count(column_name)
FROM  USER , STRUCTURE
where login_time > sysdate - 7
group by role

I would like to get the results below:

Role    7days ago    15 days ago    30 days ago    Never 
Admin   1            20             0              150

Answer 1

If you want to count users, the basic idea is conditional aggregation. Assuming that login_time and sysdate are both in the user table, you can do:

select role,
       sum(case when login_time > sysdate - 7 then 1 else 0 end) as count_07,
       sum(case when login_time > sysdate - 15 then 1 else 0 end) as count_15,
       sum(case when login_time > sysdate - 30 then 1 else 0 end) as count_30
from user u
group by role;

Why you are doing a Cartesian product between user and structure is unclear. Perhaps a join is actually needed for the data you have.

Also, it is unusual to use sysdate for this purpose, because sysdate has a time component. Normally, you just want to look at the dates.