How to calculate MTD and QTD by YTD value in Oracle - sql

Question

There are some data in my table t1 looks like below:
date dealer YTD_Value
2018-01 A 1100
2018-02 A 2000
2018-03 A 3000
2018-04 A 4200
2018-05 A 5000
2018-06 A 5500
2017-01 B 100
2017-02 B 200
2017-03 B 500
... ... ...
then I want to write a SQL to query this table and get below result:
date dealer YTD_Value MTD_Value QTD_Value
2018-01 A 1100 1100 1100
2018-02 A 2000 900 2000
2018-03 A 3000 1000 3000
2018-04 A 4200 1200 1200
2018-05 A 5000 800 2000
2018-06 A 5500 500 2500
2017-01 B 100 100 100
2017-02 B 200 100 200
2017-03 B 550 350 550
... ... ... ... ...
'YTD' means Year to date
'MTD' means Month to date
'QTD' means Quarter to date
So if I want to calculate MTD and QTD value for dealer 'A' in '2018-01', it should be the same as YTD.
If I want to calculate MTD value for dealer 'A' in '2018-06', MTD value should equal to YTD value in '2018-06' minus YTD value in '2018-05'. And the QTD value in '2018-06' should equal to YTD value in '2018-06' minus YTD value in '2018-03' or equal to sum MTD value in (2018-04,2018-05,2018-06)
The same rule for other dealers such as B.
How can I write the SQL to achieve this purpose?

Answer 1

The QTD calculation is tricky, but you can do this query without subqueries. The basic idea is to do a lag() for the monthly value. Then use a max() analytic function to get the YTD value at the beginning of the quarter.
Of course, the first quarter of the year has no such value, so a coalesce() is needed.
Try this:
with t(dte, dealer, YTD_Value) as (
select '2018-01', 'A', 1100 from dual union all
select '2018-02', 'A', 2000 from dual union all
select '2018-03', 'A', 3000 from dual union all
select '2018-04', 'A', 4200 from dual union all
select '2018-05', 'A', 5000 from dual union all
select '2018-06', 'A', 5500 from dual union all
select '2017-01', 'B', 100 from dual union all
select '2017-02', 'B', 200 from dual union all
select '2017-03', 'B', 550 from dual
)
select t.*,
(YTD_Value - lag(YTD_Value, 1, 0) over (partition by substr(dte, 1, 4) order by dte)) as MTD_Value,
(YTD_Value -
coalesce(max(case when substr(dte, -2) in ('03', '06', '09') then YTD_VALUE end) over
(partition by substr(dte, 1, 4) order by dte rows between unbounded preceding and 1 preceding
), 0
)
) as QTD_Value
from t
order by 1
Here is a db<>fiddle.

Answer 2

The following query should do the job. It uses a CTE that translates the varchar date column to dates, and then a few joins to recover the value to compare.
I tested it in this db fiddle and the output matches your expected results.
WITH cte AS (
SELECT TO_DATE(my_date, 'YYYY-MM') my_date, dealer, ytd_value FROM my_table
)
SELECT
TO_CHAR(ytd.my_date, 'YYYY-MM') my_date,
ytd.ytd_value,
ytd.dealer,
ytd.ytd_value - NVL(mtd.ytd_value, 0) mtd_value,
ytd.ytd_value - NVL(qtd.ytd_value, 0) qtd_value
FROM
cte ytd
LEFT JOIN cte mtd ON mtd.my_date = ADD_MONTHS(ytd.my_date, -1) AND mtd.dealer = ytd.dealer
LEFT JOIN cte qtd ON qtd.my_date = ADD_MONTHS(TRUNC(ytd.my_date, 'Q'), -1) AND mtd.dealer = qtd.dealer
ORDER BY dealer, my_date
PS : date is a reserved word in most RDBMS (including Oracle), I renamed that column to my_date in the query.

Answer 3

You can use lag() windows analytic and sum() over .. aggregation functions as :
select "date",dealer,YTD_Value,MTD_Value,
sum(MTD_Value) over (partition by qt order by "date")
as QTD_Value
from
(
with t("date",dealer,YTD_Value) as
(
select '2018-01','A',1100 from dual union all
select '2018-02','A',2000 from dual union all
select '2018-03','A',3000 from dual union all
select '2018-04','A',4200 from dual union all
select '2018-05','A',5000 from dual union all
select '2018-06','A',5500 from dual union all
select '2017-01','B', 100 from dual union all
select '2017-02','B', 200 from dual union all
select '2017-03','B', 550 from dual
)
select t.*,
t.YTD_Value - nvl(lag(t.YTD_Value)
over (partition by substr("date",1,4) order by substr("date",1,4) desc, "date"),0)
as MTD_Value,
substr("date",1,4)||to_char(to_date("date",'YYYY-MM'),'Q')
as qt,
substr("date",1,4) as year
from t
order by year desc, "date"
)
order by year desc, "date";
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