Table1 (ForecastProjections) design could be designed (normalized) with fields
SKU
ForecastPeriod
ForecastAmount and
valued such as
Part12,0119,15
Part12,0219,17
Part12,0319,19
....
...
Part15,0319,11
Part15,0419,12
I have changed name of your Month table to tblExportPeriod (since Month is a reserved word)
Code:
SELECT ForecastProjections.ForecastPeriod
, ForecastProjections.SKU
, ForecastProjections.ForecastAmount
FROM ForecastProjections INNER JOIN tblExportPeriod
ON ForecastProjections.ForecastPeriod = tblExportPeriod.exportMonth
ORDER BY ForecastProjections.ForecastPeriod,ForecastProjections.SKU