How to calculate payment from user's registration date plus 30 days IN ORACLE SQL - sql

Question

How to calculate payments by a certain period.
Specifically, I wonder if the user registered on the x date, how much payment he has in 30 days from that date
There are two tables:
create table user (user_id, contact, registration_date) as
select 1, 111 111, 1/18/2022 3:57:32 PM from dual union all
select 2, 222 222, 8/12/2021 12:00:12 AM from dual union all
select 3, 333 333, 12/11/2015 5:08:35 PM from dual union all
select 4, 444 444, 5/25/2020 10:59:10 AM from dual;
create table transaction (day, user_id, payment) as
select 1/20/2022, 1, 5 from dual union all
select 1/30/2022, 1, 8 from dual union all
select 2/20/2022, 1, 6 from dual union all
select 8/12/2021 , 2, 10 from dual union all
select 8/15/2021 , 2, 5 from dual union all
select 9/25/2021 , 2, 12 from dual union all
select 12/11/2015 , 3, 18 from dual union all
select 12/20/2015 , 3, 10 from dual union all
select 1/1/2016 , 3, 10 from dual union all
select 5/26/2020 , 4, 7 from dual union all
select 6/1/2020 , 4, 2 from dual;
I wonder something like this, but this query does not work,
select t.user_id,u.registration_date,sum(t.payment) from transaction t
left join user u on t.user_id = u.user_id
where t.day >= u.registration_date and t.day <= u.registration_date + interval '30' days
group by t.user_id
My expected table:
user_id
registration_date
payment
1
1/18/2022 3:57:32 PM
13
2
8/12/2021 12:00:12 AM
15
3
12/11/2015 5:08:35 PM
38
4
5/25/2020 10:59:10 AM
9

Answer 1

First of all, you probably want to outer join the transactions to the users not vice versa. Thus you also show users with no trasactions in the 30 days after registration.
Then, Oracle requires you to either put u.registration_date in GROUP BY or pseudo aggregate it (e.g. MIN(u.registration_date)). This doesn't comply with standard SQL, but it seems that Oracle hasn't mananged yet to properly detect functional dependencies, so they simply don't offer this feature.
At last, the registration date, despite its name, is not a date but a datetime. In order to compare it with the transaction date, truncate it. Then decide whether you want to include the 30th after the registration date or not (i.e. either add 30 or 31 days and use < anyway).
select u.user_id, u.registration_date, sum(t.payment)
from users u
left join transactions t
on t.user_id = u.user_id
and t.day >= trunc(u.registration_date)
and t.day < trunc(u.registration_date) + interval '31' day
group by u.user_id, u.registration_date
order by u.user_id;
Demo: https://dbfiddle.uk/?rdbms=oracle_21&fiddle=a6d8d13c994eff6a1c0f8afa6fcb176f

Answer 2

Looks like
SQL> SELECT u.user_id, u.registration_date, SUM (t.payment) payment
2 FROM tuser u JOIN transaction t ON t.user_id = t.user_id
3 WHERE t.day BETWEEN u.registration_date
4 AND u.registration_date + INTERVAL '30' DAY
5 GROUP BY u.user_id, u.registration_date
6 ORDER BY u.user_id;
USER_ID REGISTRATI PAYMENT
---------- ---------- ----------
1 01/18/2022 13
2 08/12/2021 15
3 12/11/2015 38
4 05/25/2020 9
SQL>

Answer 3

Your query doesn't work because you forgot to add the u.registration_date in your GROUP BY clause. When you do a GROUP BY, all fields mentioned in the SELECT need to be either added to the GROUP BY or be used in a aggregate function like SUM, MIN, MAX, ...