How to count incrementally in SQL Server

I am assigned a problem which I am not sure how to solve in SQL Server (version 5/8). Here is the simple query and its output:

Select location, date_time, Item_sold
From Product

Location        Date_time                   Item_sold
VA            12/10/2010 1:30:00 PM           Candy
VA            12/10/2010 3:30:00 PM           Chips
VA            12/13/2010 12:50:00 AM          Wine
DC            12/13/2010 8:00:00 AM           Gum
DC            12/13/2010 12:30:00 PM          Bags
DC            12/13/2010 1:16:00 PM           Cheese
DC            12/13/2010 12:00:00 AM          Hotdog
NJ            12/14/2010 12:00:00 AM          Coffee
NJ            12/14/2010 1:15:00 PM           Beers
NJ       开发者_运维技巧     12/14/2010 12:00:00 AM          Coffee
NJ            12/14/2010 1:45:00 PM           Water

Here is my desired output, which I guess a while/for loop or a pivot function could do the job but my experience is not there yet. Basically, I need to count the number of item sold from the Item_sold column incrementally (base line date starts from 12/8 to 12/9, 12/8 to 12/10, 12/8 to 12/11, 12/8 to 12/12...)

Location    12/10 to 12/11  12/10 to 12/12  12/10 to 12/13  12/10 to 12/14
VA               2             2                  3              3
DC               0             0                  3              3 
NJ                 0             0                  0              4

How can I solve this problem?

Sample table and data

create table Product(Location char(2), Date_time datetime, Item_sold varchar(20))
insert Product select 'VA', '20101210 1:30:00 PM' ,'Candy'
insert Product select 'VA', '20101210 3:30:00 PM' ,'Chips'
insert Product select 'VA', '20101213 12:50:00 AM' ,'Wine'
insert Product select 'DC', '20101213 8:00:00 AM' ,'Gum'
insert Product select 'DC', '20101213 12:30:00 PM' ,'Bags'
insert Product select 'DC', '20101213 1:16:00 PM' ,'Cheese'
insert Product select 'DC', '20101213 12:00:00 AM' ,'Hotdog'
insert Product select 'NJ', '20101215 12:00:00 AM' ,'Coffee'
insert Product select 'NJ', '20101215 1:15:00 PM' ,'Beers'
insert Product select 'NJ', '20101215 3:45:00 AM' ,'Cream'

The T-SQL to produce the results required

declare @start datetime
declare @end datetime
select @start = '20101208', @end = '20110105'

declare @sql nvarchar(max);
-- generate the column names
select @sql = coalesce(@sql + ',', '') + QuoteName(Convert(char(5),@start,101)+' - '+Convert(char(5),DT,101))
from (
    select @start + number DT
    from master..spt_values
    where type='P' and number between 0 and DATEDIFF(D,@start,@end)) T;

-- replace the column names into the generic PIVOT form
set @sql = REPLACE('
;with COUNTS AS (
    select p.location, Convert(char(5),@start,101)+'' - ''+Convert(char(5),@start + v.number,101) DT, X.C
    from 
    (
        Select distinct location From Product
        where Date_time >= @start and Date_time < @end+1 -- * the date after, to handle the times
    ) p
    inner join master..spt_values v on v.type=''P'' and v.number between 0 and DATEDIFF(D,@start,@end)
    cross apply
    (
        select COUNT(*) C from product p2
        where p2.Location=p.Location
        and p2.date_time >= @start and p2.date_time < @start + v.number +1
    ) X
)
select location, :columns:
from COUNTS p
pivot (max(C) for DT in (:columns:)) pv',
':columns:', @sql)

-- execute for the results
exec sp_executesql @sql, N'@start datetime,@end datetime', @start, @end

The above, from cyberkiwi, is too complicated. You need to do something called a 'table rotation'. Assuming you have a product table like this:

create table product
(
  location  char(2)     not null ,
  date_time datetime    not null ,
  item_sold varchar(32) not null ,

  primary key clustered ( location , date_time ) ,
)

The sql you want is the following SELECT statement:

select Location       = loc.location  ,
       "12/8"         =  t8.sales_cnt ,
       "12/8 - 12/09" =  t9.sales_cnt ,
       "12/8 - 12/10" = t10.sales_cnt ,
       "12/8 - 12/11" = t11.sales_cnt ,
       "12/8 - 12/12" = t12.sales_cnt ,
       "12/8 - 12/13" = t13.sales_cnt
from      ( select distinct location from #product ) loc
left join ( select location , sales_cnt = count(*) from #product where date_time between '2011-12-08 00:00:00.000' and '2011-12-08 23:59:59.997' group by location ) t8  on t8.location  = loc.location
left join ( select location , sales_cnt = count(*) from #product where date_time between '2011-12-08 00:00:00.000' and '2011-12-09 23:59:59.997' group by location ) t9  on t9.location  = loc.location
left join ( select location , sales_cnt = count(*) from #product where date_time between '2011-12-08 00:00:00.000' and '2011-12-10 23:59:59.997' group by location ) t10 on t10.location = loc.location
left join ( select location , sales_cnt = count(*) from #product where date_time between '2011-12-08 00:00:00.000' and '2011-12-11 23:59:59.997' group by location ) t11 on t11.location = loc.location
left join ( select location , sales_cnt = count(*) from #product where date_time between '2011-12-08 00:00:00.000' and '2011-12-12 23:59:59.997' group by location ) t12 on t12.location = loc.location
left join ( select location , sales_cnt = count(*) from #product where date_time between '2011-12-08 00:00:00.000' and '2011-12-13 23:59:59.997' group by location ) t13 on t13.location = loc.location
order by 1