Sum amount within a date range

Question

I have 2 tables where I Need to sum up sales amount within a booking date range.
Below an example to help illustrate this task.
Table1:
CustomerID BookingDate (YYYY-MM-DD)
1 2014-04-29
1 2014-07-30
2 2014-03-31
2 2014-06-30
Table2:
CustomerID SalesDate (YYYY-MM-DD) Amount
1 2014-01-30 20
1 2014-02-25 30
1 2014-05-20 100
1 2014-07-30 200
1 2014-09-30 80
2 2014-03-20 50
Result:
CustomerID BookingDate (YYYY-MM-DD) Sum(Amount From Table2)
1 2014-04-29 50 -- SalesDate between 2014-01-01 and 2014-04-29
1 2014-07-30 300 -- SalesDate between 2014-04-30 and 2014-07-30
2 2014-03-31 50 -- SalesDate between 2014-01-01 and 2014-03-31
2 2014-06-30 0 -- SalesDate between 2014-04-01 and 2014-06-30

Answer 1

Please try this code:
declare @Table1 table
(CustomerID int,BookingDate date );
insert @Table1
values
( 1, '2014-04-29' ),
(1, '2014-07-30' ),
(2, '2014-03-31' ),
(2, '2014-06-30') ;
declare @Table2 table
(CustomerID int, SalesDate date, Amount int);
insert @Table2
values
(1,'2014-01-30',20) ,
(1,'2014-02-25',30) ,
(1,'2014-05-20',100) ,
(1,'2014-07-30',200) ,
(1,'2014-09-30',80) ,
(2,'2014-03-20',50) ;
with cte as
select
CustomerID,
BookingDate ,
row_number() over (partition by CustomerID order by BookingDate ) as rn
from @Table1 )
, cte2 as
select
T2.CustomerID ,
isnull(T1.BookingDate, '2014-01-01') as FromDate,
T2.BookingDate as ToDate
from cte as T1
right join cte as T2
on T1.rn = T2.rn - 1
and T1.CustomerID = T2.CustomerID
select
b.CustomerID ,
b.ToDate as BookingDate,
isnull(sum(a.Amount), 0) as [Sum(Amount From Table2)]
from @Table2 as a
right join cte2 as b
on a.CustomerID = b.CustomerID
and a.SalesDate > b.FromDate
and a.SalesDate <= b.ToDate
group by
b.CustomerID ,
b.ToDate;
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