Question

I have two tables:

first one (amount):

  amountid      date         amount
    1         01.01.2011      100
    2         02.01.2011       50
    3         04.01.2011      200
    4         10.01.2011      20
    5         11.01.2011      5

second one (period):

  periodid      date
     1          01.01.2011
     2          03.01.2011
     3          05.01.2011

I need group first table by times from second table, and sum (amount):

for this example answer is:

      01.01.2011    150
      03.01.2011    200  
      05.01.2011    25

help me with sql query please.

Answer 1

Sample data

declare @Amount table
(
  amountid int,
  [date] datetime,
  amount int
)

declare @Period table
(
  periodid int,
  [date] datetime
)

insert into @Amount
select 1, '20110101', 100 union all
select 2, '20110102', 50  union all
select 3, '20110104', 200 union all
select 4, '20110110', 20  union all
select 5, '20110111', 5

insert into @Period
select 1, '20110101' union all
select 2, '20110103' union all
select 3, '20110105'

The query

select P.StartDate,
       sum(A.amount) as amount
from (
      select P1.[date] as StartDate,
             coalesce((select min(P2.[date])
                       from @Period as P2
                       where P1.[date] < P2.[date]), '99991231') as endDate
      from @Period as P1
     ) as P      
  inner join @Amount as A
    on A.[date] >= P.StartDate and 
       A.[date] < P.EndDate
group by P.StartDate