dynamic grouping by in sql server - sql

Question

i want to make a stored procedure like makeGroupBy(#a int,#b int,#c int). The inputs are 0 or 1 to decide which columns to group by. My attempt so far is below:
-- exec makeGroupBy 0,1,0
-- exec makeGroupBy 0,1,1
create proc makeGroupBy(#product_id int = 0,#city_id int = 1,#date_key
int = 0) as
begin
declare #tbl as table(product_id int, city_id int, date_key int, amount
float)
insert into #tbl
values(1,1,1,10),
(1,1,1,10),
(1,2,1,5),
(2,2,3,15),
(2,1,3,20),
(3,1,1,25)
select case isnull(#product_id,0) when 0 then 0 else product_id end
,case isnull(#city_id,0) when 0 then 0 else city_id end
,case isnull(#date_key,0) when 0 then 0 else date_key end
, sum(amount) amount from #tbl
group by case isnull(#product_id,0) when 0 then 0 else product_id end
,case isnull(#city_id,0) when 0 then 0 else city_id end
,case isnull(#date_key,0) when 0 then 0 else date_key end
end
I don't know if it's possible but what I want is to omit the unwanted columns (inputs with value 0) in the result set.

Answer 1

Assuming that your sql-server version is greater or equal than 2008.
select
product_id
,city_id
,date_key
,sum(amount) as total_amount
from #tbl
group by grouping sets (
(product_id, city_id, date_key)
, (product_id,city_id)
, (product_id, date_key)
, (city_id, date_key)
, (product_id)
, (city_id)
, (date_key))
having concat(iif(grouping_id(product_id)=0,1,0),iif(grouping_id(city_id)=0,1,0),iif(grouping_id(date_key)=0,1,0)) = concat(#product_id, #city_id, #date_key)
order by concat(iif(grouping_id(product_id)=0,1,0),iif(grouping_id(city_id)=0,1,0),iif(grouping_id(date_key)=0,1,0))
It seems that a view will probably suit best for this case
create view [view_name]
as
select
product_id
,city_id
,date_key
,sum(amount) as amount
,concat(iif(grouping_id(product_id)=0,1,0),iif(grouping_id(city_id)=0,1,0),iif(grouping_id(date_key)=0,1,0)) as grp_key
from #tbl
group by grouping sets (
(product_id, city_id, date_key)
, (product_id,city_id)
, (product_id, date_key)
, (city_id, date_key)
, (product_id)
, (city_id)
, (date_key))
go
Then you can query the view like
select
city_id
,date_key
,amount
from [view_name]
where grp_key = concat(0,1,1)