Query that sums multiple fields which need to change each month

[bullwinkle55423]

I have two tables (see attachment)


One (tbl_Sales) has sales for different offices with a different value for each month in different columns (eg Jan, Feb, Mar, etc..)
The second (tbl_Months) list a month number.

Is it possible to write a query that will sum the columns in tbl_Sales based on the month number in tbl_Months? For example, if the month number is 2, then the query needs to sum Jan and Feb.

The goal is to be able to change the month number each month instead of rewriting the queries each month.

tbl_Months can be restructured in any format that will make the query more effective.

Thanks for your help.

[orange]

You are building a spreadsheet not a database.
Construct a data model and Normalize you tables

I see at least these tables.
Office
OfficeSales
MonthInvolved

You will probably need to keep Year in the table as well unless this is a 1 year design.
An Office has 1 or more Sales each Month