SQL Query for Normalized Sales - sql

Question

I need to write an SQL query that solves this problem:
"Get the top 10 departments overall ranked by total sales normalized by the size
of the store where the sales were recorded."
Normalizing the sales means to divide the number of sales by the size of the store per sale. So in other words I need a query that returns the top 10 departments with the greatest sum of WeeklySales/size for every sale by that department. Eg: (week1sales/size1) + (week2sales/size2) + ...
Here is the data in the database where bolded attributes are keys.
-Holidays (WeekDate, IsHoliday)
-Stores (Store, Type, Size)
-TemporalData (Store, WeekDate, Temperature, FuelPrice, CPI, UnemploymentRate)
-Sales (Store, Dept, WeekDate, WeeklySales)
(WeekDate is the date for the first day of the week. WeeklySales is an integer for the number of sales that week.)
The main issue I'm having with writing this query is that I'm having troubles figuring out how to find the sum of all sales by each department. How would keep track of the total normalized sales for each department in a query and then add them all together? Also this query will have to run in SQLite3 if that makes any difference.
Edit: Explained normalized in this context.

Answer 1

Your question isnt clear but for one single week you need something like this
SELECT *
FROM (
SELECT Sa.Store, Sa.Dept, SUM(WeeklySales) / St.Size as normalized
FROM Sales Sa
JOIN Stores St
ON Sa.Store = St.Store
WHERE Sa.WeekDate = #date#
GROUP BY Sa.Store, Sa.Dept
) AS T
ORDER BY normalized DESC
LIMIT 10
If you want the comulative for all weeks
SELECT *
FROM (
SELECT Sa.Store, Sa.Dept, SUM(WeeklySales) / St.Size as normalized
FROM Sales Sa
JOIN Stores St
ON Sa.Store = St.Store
GROUP BY Sa.Store, Sa.Dept
) AS T
ORDER BY normalized DESC
LIMIT 10