Dealing with consecutive rows calculations - sql

Question

Assume the following situation:
Week 1:
0 previous cases
10 new cases
3 resolved cases
Week 2:
7 previous cases
13 new cases
15 resolved cases
Week 3:
5 previous cases
6 new cases
7 resolved cases
This information is stored in a resumed table of the sort:
RESUME_TABLE:
WEEK | TOTAL_NEW | TOTAL_SOLVED
1 | 10 | 3
2 | 13 | 15
3 | 6 | 7
I am having a hard time build a query to obtain the following result:
REPORT_TABLE:
WEEK | PREV_TOTAL | NEW_CASES | SOLVED_CASES | NEW_TOTAL
1 | 0 | 10 | 3 | 7
2 | 7 | 13 | 15 | 5
3 | 5 | 6 | 7 | 4
The idea seems pretty trivial, NEW_TOTAL = PREV_TOTAL + NEW_CASES - SOLVED_CASES, though I have been struggling with the idea of carrying the PREV_TOTAL to the next row in order to go on.
I am trying to do it using a view over the RESUME table (Oracle 11g).
Can someone help me with some example code?

Answer 1

Pretty simple and neat with analytic functions:
12:57:06 HR#vm_xe> l
1 select week
2 ,lag(total_cases_by_now - total_solved_by_now) over (order by week) prev_total
3 ,total_new new_cases
4 ,total_solved solved_cases
5 ,total_cases_by_now - total_solved_by_now new_total
6 from (
7 select week
8 ,total_new
9 ,total_solved
10 ,sum(total_new) over(order by week asc) as total_cases_by_now
11 ,sum(total_solved) over (order by week asc) as total_solved_by_now
12 from resume_table
13* )
12:57:07 HR#vm_xe> /
WEEK PREV_TOTAL NEW_CASES SOLVED_CASES NEW_TOTAL
---------- ------------ ---------- ------------ ----------
1 10 3 7
2 7 13 15 5
3 5 6 7 4
3 rows selected.
Elapsed: 00:00:00.01

Answer 2

You can solve this with MODEL clause:
with resume_table as
(
select 1 week, 10 total_new, 3 total_solved from dual union all
select 2 week, 13 total_new, 15 total_solved from dual union all
select 3 week, 6 total_new, 7 total_solved from dual
)
select week, prev_total, total_new, total_solved, new_total
from resume_table
model
dimension by (week)
measures (total_new, total_solved, 0 prev_total, 0 new_total)
rules sequential order
(
new_total[any] order by week =
nvl(new_total[cv(week)-1], 0) + total_new[cv()] - total_solved[cv()]
,prev_total[any] order by week = nvl(new_total[cv(week)-1], 0)
)
order by week;
Although this makes the assumption that WEEK is always a consecutive number. If that's not true, you will want to add a row_number(). Otherwise, the -1 may not reference the previous value.
See this SQL Fiddle.

Answer 3

Add one column in RESUME_TABLE (or create a view, which I think may be better):
RESUME_LEFT
WEEK | LEFT
1 | 7
2 | -2
3 | -1
Something like this:
CREATE VIEW resume_left
(SELECT week,total_new-total_solved "left" FROM resume_table)
So in REPORT_TABLE, you can have an definition like this:
PREV_TOTAL=(SELECT sum(left) FROM RESUME_LEFT WHERE week<REPORT_TABLE.week)
Edit
OK, the view is unnecessary:
PREV_TOTAL=(SELECT sum(total_new)-sum(total_solved)
FROM resume_table
WHERE week<REPORT_TABLE.week)