ssrs hidden rows are getting summed - sql

Question

I am fairly new to SSRS and SQL Server and I need help with the following issue:
I have two tables. One contains the time stamped record of purchases of one single product by a small group of customers. The other table contains the time stamped record of price changes for that product.
Table1
PurchaseDateTime - primary key,
CustCode, kgs
Table2
Price, ChangeDateTime
I can display all required information from the two tables in a tablix using the following query:
SELECT input.purchasedatetime,
input.custcode,
input.kgs,
price.price,
price.changedatetime
FROM input
LEFT OUTER JOIN price
ON input.purchasedatetime > price.changedatetime
However, the query correctly returns the results which includes the superseded prices as well. I could hide those rows, but the totals still sum it all. I could group it by the Price.ChangeDateTime as the third subgroup and then filter it on TopN, but the result is the same. The display is correct, the totals are not, which is probably to be expected since the totals are on the higher level grouping.
I cannot apply the conditions for the visibility to the SUM() as it does not allow aggregates and I am hiding on Previous().
I would prefer the query to do the complete work and I have seen that some other databases implement the LIMIT 1 clause, but here this is not supported.
I am still to try the custom code on the report level, but I am not too familiar with VB code.
I am using the SQL Server 2014 Express and Visual Studio 2013 integrated shell as Data Tools or BI
Any help is much appreciated.

Answer 1

you can get maximum change date time for each purchase time using GROUP BY and MAX
These values can be joined further to get price for each purchase time
SQL Fiddle
with cte
as
(
SELECT input.purchasedatetime, MAX(price.changedatetime) as ChangeDateTime
FROM input
LEFT OUTER JOIN price
ON input.purchasedatetime > price.changedatetime
GROUP BY input.purchasedatetime
)
SELECT input.purchasedatetime,
input.custcode,
input.kgs,
price.price,
price.changedatetime
FROM input
JOIN cte
on input.purchasedatetime = cte.purchasedatetime
left join price
on cte.changedatetime = price.changedatetime