SQL Server 2019

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create table t
(
  Customer  varchar(5),
  StartDay date,
  EndDay date,
  Product  varchar(5),
  Cost  decimal(10,2)
);

insert into t values 
('A',       '1/1/2019',      '1/4/2019',      'Shoe',        10.00),
('B',       '2/4/2021',      '2/7/2021',      'Hat',          10.00),
('A',       '1/7/2019',      '1/8/2019',      'Shoe',        10.00),
('B',       '5/8/2018',      '5/9/2018',      'Shoe',         10.00),
('A',       '2/1/2019',      '2/3/2019',      'Shoe',        10.00),
('C',       '6/6/2020',      '6/6/2020',      'Hat',         10.00),
('C',       '11/9/2021',     '12/9/2021',     'Cloth',       10.00),
('A',       '3/3/2019',      '3/17/2019',     'Cloth',        10.00),
('C',       '7/8/2020',      '7/12/2020',      'Hat',         10.00),
('E',       '7/2/2020',      '9/1/2020',      'Hat',        10.00),
('A',       '3/3/2019',      '3/7/2019',      'Shoe',        10.00),
('A',       '7/5/2022',      '7/9/2022',      'Hat',       10.00),
('C',       '6/6/2020',      '6/8/2020',      'Shoe',        10.00),
('B',       '8/2/2018',      '8/9/2018',      'Shoe',         10.00),
('A',       '1/1/2019',      '1/11/2019',     'Cloth',        10.00),
('E',       '9/3/2020',      '10/1/2020',      'Hat',        10.00),
('E',       '7/2/2020',      '7/8/2020',      'Shoe',       10.00);
17 rows affected

select *
from   t
order by Customer, Product, 	StartDay


Customer
StartDay
EndDay
Product
Cost


A
2019-01-01
2019-01-11
Cloth
10.00

A
2019-03-03
2019-03-17
Cloth
10.00

A
2022-07-05
2022-07-09
Hat
10.00

A
2019-01-01
2019-01-04
Shoe
10.00

A
2019-01-07
2019-01-08
Shoe
10.00

A
2019-02-01
2019-02-03
Shoe
10.00

A
2019-03-03
2019-03-07
Shoe
10.00

B
2021-02-04
2021-02-07
Hat
10.00

B
2018-05-08
2018-05-09
Shoe
10.00

B
2018-08-02
2018-08-09
Shoe
10.00

C
2021-11-09
2021-12-09
Cloth
10.00

C
2020-06-06
2020-06-06
Hat
10.00

C
2020-07-08
2020-07-12
Hat
10.00

C
2020-06-06
2020-06-08
Shoe
10.00

E
2020-07-02
2020-09-01
Hat
10.00

E
2020-09-03
2020-10-01
Hat
10.00

E
2020-07-02
2020-07-08
Shoe
10.00


select  Customer	
       ,StartDay	
       ,EndDay	
       ,Product	
       ,Cost
       ,[0]                  as '0-30 days'
       ,[0] + [1]            as '0-60 days'
       ,[0] + [1] + [2]      as '0-90 days'
       ,[0] + [1] + [2]+ [3] as 'total'
from
(
select  t.Customer
       ,t.StartDay
       ,t.EndDay
       ,t.Product
       ,t.Cost
       ,case when (datediff(day, t.EndDay, t2.StartDay)-1)/30 > 3 then 3 else (datediff(day, t.EndDay, t2.StartDay)-1)/30 end as dd
from    t left join t t2 on  t2.Customer = t.Customer 
                         and t2.Product = t.Product
                         and t2.StartDay > t.EndDay
) t
pivot(count(dd) for dd in([0],[1],[2],[3])) p
order by Customer, Product, StartDay


Customer
StartDay
EndDay
Product
Cost
0-30 days
0-60 days
0-90 days
total


A
2019-01-01
2019-01-11
Cloth
10.00
0
1
1
1

A
2019-03-03
2019-03-17
Cloth
10.00
0
0
0
0

A
2022-07-05
2022-07-09
Hat
10.00
0
0
0
0

A
2019-01-01
2019-01-04
Shoe
10.00
2
3
3
3

A
2019-01-07
2019-01-08
Shoe
10.00
1
2
2
2

A
2019-02-01
2019-02-03
Shoe
10.00
1
1
1
1

A
2019-03-03
2019-03-07
Shoe
10.00
0
0
0
0

B
2021-02-04
2021-02-07
Hat
10.00
0
0
0
0

B
2018-05-08
2018-05-09
Shoe
10.00
0
0
1
1

B
2018-08-02
2018-08-09
Shoe
10.00
0
0
0
0

C
2021-11-09
2021-12-09
Cloth
10.00
0
0
0
0

C
2020-06-06
2020-06-06
Hat
10.00
0
1
1
1

C
2020-07-08
2020-07-12
Hat
10.00
0
0
0
0

C
2020-06-06
2020-06-08
Shoe
10.00
0
0
0
0

E
2020-07-02
2020-09-01
Hat
10.00
1
1
1
1

E
2020-09-03
2020-10-01
Hat
10.00
0
0
0
0

E
2020-07-02
2020-07-08
Shoe
10.00
0
0
0
0

Customer	StartDay	EndDay	Product	Cost
A	2019-01-01	2019-01-11	Cloth	10.00
A	2019-03-03	2019-03-17	Cloth	10.00
A	2022-07-05	2022-07-09	Hat	10.00
A	2019-01-01	2019-01-04	Shoe	10.00
A	2019-01-07	2019-01-08	Shoe	10.00
A	2019-02-01	2019-02-03	Shoe	10.00
A	2019-03-03	2019-03-07	Shoe	10.00
B	2021-02-04	2021-02-07	Hat	10.00
B	2018-05-08	2018-05-09	Shoe	10.00
B	2018-08-02	2018-08-09	Shoe	10.00
C	2021-11-09	2021-12-09	Cloth	10.00
C	2020-06-06	2020-06-06	Hat	10.00
C	2020-07-08	2020-07-12	Hat	10.00
C	2020-06-06	2020-06-08	Shoe	10.00
E	2020-07-02	2020-09-01	Hat	10.00
E	2020-09-03	2020-10-01	Hat	10.00
E	2020-07-02	2020-07-08	Shoe	10.00