SELECT *,
SUM( `Janunits` + `Febunits` + `Marunits` + `Aprunits` + `Mayunits` + `Jununits` + `Julunits` + `Augunits` + `Sepunits` + `Octunits` + `Novunits` + `Decunits` ) AS TotalUnits,
SUM ( `TotalUnits` - `inventory.Year1qty` ) / `inventory.Year1qty` AS Percent
FROM `inventory`
WHERE `Dept` = 'WIDGETS'
GROUP BY Item
didn't you want to use `inventory.Year1qty` anyway for percent? It appears you wouldn't ever have devide by zero at that point.
Another observation... the last error you got was an error in the GROUP BY.
Does the query:
SELECT *,
SUM( `Janunits` + `Febunits` + `Marunits` + `Aprunits` + `Mayunits` + `Jununits` + `Julunits` + `Augunits` + `Sepunits` + `Octunits` + `Novunits` + `Decunits` ) AS TotalUnits,
SUM ( `TotalUnits` - `inventory.Year1qty` ) AS PercentTop, `TotalUnits` AS PercentDivide
FROM `inventory`
WHERE `Dept` = 'WIDGETS'
GROUP BY Item
return what you expect?