Question

I have a table Information which is something like this:

ID    From     To        Product          Date  
1         A         B          ProdA         2012-10-01  
2         A         B          ProdA         2012-10-13  
3         A         B          ProdB         2012-10-17  
4         A         B          ProdC         2012-10-18  
5         A         C          ProdB         2012-10-02  
6         A         C          ProdC         2012-10-04  
7         A         C          ProdD         2012-10-12  
8         A         C          ProdE         2012-10-14  
9         A         D          ProdA         2012-10-11  
10       A         D          ProdA         2012-10-14  

Let’s call the combination of From and To a relationship. So (A,B) and (A, C) are relationships.
What I need to do is to find those relationships sending/receiving different products within a week time period. So in the above example the query is supposed to return:

A    B
A    C

since these rows match:

2         A         B          ProdA         2012-10-13  
3         A         B          ProdB         2012-10-17  
4         A         B          ProdC         2012-10-18  

5         A         C          ProdB         2012-10-02  
6         A         C          ProdC         2012-10-04  

7         A         C          ProdD         2012-10-12  
8         A         C          ProdE         2012-10-14  

I know I should start from SELECT ID, From, To, Product, Date FROM Information GROUP BY From, To but I have no idea what’s next. Any help please?

Answer 1

something like this perhaps:

declare @t table(id int identity(1,1), [from] char default 'A', [to] char, product char(5), date date)
-- populating testdata works with sql server 2008+
insert @t ([to],product, date) values
('B','ProdA','2012-10-01'),('B','ProdA','2012-10-13'),
('B','ProdB','2012-10-17'),('B','ProdC','2012-10-18'),
('C','ProdB','2012-10-02'),('C','ProdC','2012-10-04'),
('C','ProdD','2012-10-12'),('C','ProdE','2012-10-14'),
('D','ProdA','2012-10-11'),('D','ProdA','2012-10-14')


select * from @t t where exists 
(select 1 from @t where t.[from] = [from] and t.[to] = [to] and 
t.product <> product and t.date between dateadd(day, -7, date) and 
dateadd(day, 7, date))