SQL - Use DATEADD in GROUP BY (?)

Question

Im working on a query that is meant to retrive sales by hour, which it does. However, in the used database table all the timestamps are UTC +1 , also for sales made in a country with UTC +2 .

So what I'm trying to achive is a result that can be used by local business units (a parameter is set depending on who is looking at a report will determine the which country/store to display). So when it's sales in a UTC +2 country the datestamp needs to be modified with +1. I'm thinking this can be done in the group by, perhaps by using a DATEADD together with a condition that checks the county name. For example, when the country is 'Greece' (column exists in the database), use a DATEADD to add 1 hour to the timestamp.
Is this a possible solution and if so, how is it done?

This is the GROUP BY im using at the moment:

SELECT
DATEPART(hour, sales.OrderDate) AS Hour,
SUM(CASE WHEN FORMAT(sales.OrderDate, 'yyyy-MM-dd') = Cast(GETDATE() AS date) THEN sales.SALES * (1 + sales.vv / 100) END) AS SALES, 
COUNT(DISTINCT (CASE WHEN FORMAT(sales.OrderDate, 'yyyy-MM-dd') = Cast(GETDATE() AS date) THEN sales.OID END) ) AS CUSTOMERS,
MAX(CASE WHEN FORMAT(sv.Date_Time, 'yyyy-MM-dd') = Cast(GETDATE() AS date) THEN sv.CC END) AS VISITORS

FROM
[DW].[Tot_Sales] AS sales
LEFT JOIN [DW].[SV_24M] AS sv ON dateadd(hour, datediff(hour, 0, sales.[OrderDate]), 0) = dateadd(HOUR, 0, sv.Date_Time)
AND sales.SID = sv.SID

WHERE 
sales.SID = @Store 
AND FORMAT(sales.OrderDate, 'yyyy-MM-dd') > DATEADD(year, - 1, Cast(GETDATE() AS date))

GROUP BY 
sales.SID, 
DATEPART(hour, sales.OrderDate)

ORDER BY 
DATEPART(hour, sales.OrderDate)

It is in the columns SALES and CUSTOMERS this needs to be applied, and they are from the table named sales . This is how the result looks:

Resultset

The issue is that the sales and customers occuring at hour 9 actually occured hour 10 in UCT +2 . Visitors data arrives in local time ( UCT +2 in this case), and therefore it's a mismatch between Visitors and Customers.

Sample data set:

Dataset

Answer 1

If you know the countries then you could make use of AT TIME ZONE in the query to set the appropriate local time.

Refer to this