| Building the SUM, MIN, or MAX .. of over a grouped set of Records this is very easy.
Invenstment | Year | InterestPrevYear
--------------------------------------
Warehouse_1 | 2004 | 1,05
Warehouse_1 | 2005 | 1,2
Warehouse_1 | 2006 | 1,3
SELECT investment, SUM(InterestPrevYear)
FROM sales.revenue_year
GROUP BY investment
--> Warehouse_1 | 3,55
We want to build the product to charge the interest over the last 3 years, the SUM or any other kown aggregte function is not correct in this case.
We must build the product to charge the interest!
Remember: a*b*c = exp(Log(a*b*c )) = exp(log(a) + log(b) + log(c))
SELECT investment, EXP(SUM(LOG(PercRevenueYear)))
FROM sales.revenue_year
GROUP BY investment
--> Warehouse_1 | 1,638
THIS IS IT!!
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