Date Range Report - Aggregation - sql

Question

I have a few issues doing a typical report style SQL that I’m hoping someone with more experience might be able to help with.
I have the following tables
products
product_id
product_name
product_category
product_defects
product_id
defect_date
high_priority
med_priority
low_priority
calendar
date
And what I want is to be able to generate a report that outlines the number of high / medium / low defects associated with each product category on each day e.g – even though data may not exist in product_defect for a particular day, in which case it should be returned as 0. Example:
product_category | date | high | medium | low
1 2012-10-01 1 5 6
2 2012-10-01 2 4 3
3 2012-10-01 1 5 6
1 2012-10-02 0 0 0
2 2012-10-02 2 4 3
3 2012-10-02 1 5 6
…
What I’ve done so far is:
Create a lookup table called calendar which has a series of days in it going back/forward several years
Right joined the lookup/product_defects table to get a series of dates so missing days can be marked as 0
Used COALESCE and SUM to calculate totals and change any missing data to 0
Used MIN / MAX on the defect_date to get the exact report range
I've banged my head on this for a few days now, hoping someone can help.
Thank you

Answer 1

You need to start with all combinations of products and dates, and then join in the defects:
select p.product_category, c.date,
coalesce(SUM(high_priority), 0) as high_priority,
coalesce(SUM(med_priority), 0) as med_priority,
coalesce(SUM(low_priority), 0) as low_priority
from product p cross join
calendar c left outer join
product_defects pd
on pd.product_id = p.product_id and
pd.date = c.date
group by p.product_category, c.date
order by 2, 1
(Note: this is untested, so may have syntax errors.)

Answer 2

something like this. I used dual instead of calendar which you can use or substitute calendar table.
eg with start date as 01-jan-2013 through to 15th jan 2013.
with dates as (select to_date('01/01/2013', 'dd/mm/yyyy') + rownum - 1 dte
from dual
connect by level <= to_date('15/01/2013', 'dd/mm/yyyy')
- to_date('01/01/2013', 'dd/mm/yyyy') + 1)
select dt.dte, p.product_id, p.product_name,
sum(d.high_priority), sum(d.med_priority), sum(d.low_priority)
from products p
inner join product_defects d
on d.product_id = p.product_id
right outer join dates dt
on dt.dte = d.defect_date -- trunc(d.defect_date) if you store with a time element.
group by dt.dte, p.product_id, p.product_name
order by dt.dte;

Answer 3

So this uses a sub-factory querying clause (cte) to aggregate all the defects for each category for each day. I used this construct to make the logic clearer; there are other ways to do it. The sub-query is then outer-joined to the calendar table.
with cte as
( select p.product_category
, d.defect_date
, sum(pd.high_priority) as high_priority
, sum(pd.med_priority) as med_priority
, sum(pd.low_priority) as low_priority
from product p
join product_defect pd
on (pd.product_id = p.product_id )
group by p.product_category
, d.defect_date )
select cte.product_category
, cal.date
, nvl(cte.high_priority, 0) as high_priority
, nvl(cte.med_priority, 0) as med_priority
, nvl(cte.low_priority, 0) as low_priority
from calendar cal
left outer join cte
on cal.date = cte.defect_date
order by cte.product_category
, cal.date

Answer 4

Calendar table example only. Increase the number of months back from -24 (2 years) to any number - copy/paste the code:
-- 2 years back by date --
SELECT TRUNC(SYSDATE, 'YEAR') - LEVEL AS mydate
FROM dual
CONNECT BY LEVEL <= TRUNC(SYSDATE, 'yy') - TRUNC(Add_Months(SYSDATE, -24), 'yy')
/
Add more dates:
-- 2 years back by date and week --
SELECT mydate
, TRUNC(mydate, 'iw') wk_starts
, TRUNC(mydate, 'iw') + 7 - 1/86400 wk_ends
, TO_NUMBER (TO_CHAR (mydate, 'IW')) ISO_wk#
FROM
(
SELECT TRUNC(SYSDATE, 'YEAR') - LEVEL AS mydate
FROM dual
CONNECT BY LEVEL <= TRUNC(SYSDATE, 'yy') - TRUNC(Add_Months(SYSDATE, -24), 'yy')
)
/
Post create table and inserts scripts to answer the rest of your questions or use sqlfiddle...