Query to find active days per year to find revenue per user per year - sql

Question

I have 2 dimension tables and 1 fact table as follows:
user_dim
user_id
user_name
user_joining_date
1
Steve
2013-01-04
2
Adam
2012-11-01
3
John
2013-05-05
4
Tony
2012-01-01
5
Dan
2010-01-01
6
Alex
2019-01-01
7
Kim
2019-01-01
bundle_dim
bundle_id
bundle_name
bundle_type
bundle_cost_per_day
101
movies and TV
prime
5.5
102
TV and sports
prime
6.5
103
Cooking
prime
7
104
Sports and news
prime
5
105
kids movie
extra
2
106
kids educative
extra
3.5
107
spanish news
extra
2.5
108
Spanish TV and sports
extra
3.5
109
Travel
extra
2
plans_fact
user_id
bundle_id
bundle_start_date
bundle_end_date
1
101
2019-10-10
2020-10-10
2
107
2020-01-15
(null)
2
106
2020-01-15
2020-12-31
2
101
2020-01-15
(null)
2
103
2020-01-15
2020-02-15
1
101
2020-10-11
(null)
1
107
2019-10-10
2020-10-10
1
105
2019-10-10
2020-10-10
4
101
2021-01-01
2021-02-01
3
104
2020-02-17
2020-03-17
2
108
2020-01-15
(null)
4
102
2021-01-01
(null)
4
103
2021-01-01
(null)
4
108
2021-01-01
(null)
5
103
2020-01-15
(null)
5
101
2020-01-15
2020-02-15
6
101
2021-01-01
2021-01-17
6
101
2021-01-20
(null)
6
108
2021-01-01
(null)
7
104
2020-02-17
(null)
7
103
2020-01-17
2020-01-18
1
102
2020-12-11
(null)
2
106
2021-01-01
(null)
7
107
2020-01-15
(null)
note: NULL bundle_end_date refers to active subscription.
user active days can be calculated as: bundle_end_date - bundle_start_date (for the given bundle)
total revenue per user could be calculated as : total no. of active days * bundle rate per day
I am looking to write a query to find revenue generated per user per year.
Here is what I have for the overall revenue per user:
select pf.user_id
, sum(datediff(day, pf.bundle_start_date, coalesce(pf.bundle_end_date, getdate())) * bd.price_per_day) total_cost_per_bundle
from plans_fact pf
inner join bundle_dim bd on bd.bundle_id = pf.bundle_id
group by pf.user_id
order by pf.user_id;

Answer 1

You need a 'year' table to help parse out each multi-year spanning row into it's seperate years. For each year, you need to also recalculate the start and end dates. That's what I do in the yearParsed cte in the code below. I hard code the years into the join statement that creates y. You probably will do it different but however you get those values will work.
After that, pretty much sum as you did before, just adding the year column to your grouping.
Aside from that, all I did was move the null coalesce logic to the cte to make the overall logic simpler.
with yearParsed as (
select pf.*,
y.year,
startDt = iif(pf.bundle_start_date > y.startDt, pf.bundle_start_date, y.startDt),
endDt = iif(ap.bundle_end_date < y.endDt, ap.bundle_end_date, y.endDt)
from plans_fact pf
cross apply (select bundle_end_date = isnull(pf.bundle_end_date, getdate())) ap
join (values
(2019, '2019-01-01', '2019-12-31'),
(2020, '2020-01-01', '2020-12-31'),
(2021, '2021-01-01', '2021-12-31')
) y (year, startDt, endDt)
on pf.bundle_start_date <= y.endDt
and ap.bundle_end_date >= y.startDt
)
select yp.user_id,
yp.year,
total_cost_per_bundle = sum(datediff(day, yp.startDt, yp.endDt) * bd.bundle_cost_per_day)
from yearParsed yp
join bundle_dim bd on bd.bundle_id = yp.bundle_id
group by yp.user_id,
yp.year
order by yp.user_id,
yp.year;
Now, if this is common, you should probably create a base-table for your 'year' table. But if it's not common, but for this report you don't want to have to keep coming back to hard-code the year information into the y table, you can do this:
declare #yearTable table (
year int,
startDt char(10),
endDt char(10)
);
with y as (
select year = year(min(pf.bundle_start_date))
from #plans_fact pf
union all
select year + 1
from y
where year < year(getdate())
)
insert #yearTable
select year,
startDt = convert(char(4),year) + '-01-01',
endDt = convert(char(4),year) + '-12-31'
from y;
and it will create the appropriate years for you. But you can see why creating a base table may be preferred if you have this or a similar need often.