>Why doesn't this work? I'm trying to first compute NetAmount, then use it in the next column:
>
>

>
>SELECT	t.decTrade_Ext_Price + t.decTrade_Shipping_Charge + t.decTrade_Other_Charge AS NetAmount,
>		(t.decTrade_Product_Balance / t.decTrade_Qty) * NetAmount AS NotShip
>	FROM Trade t
>	JOIN Trading_Partner tp ON tp.iTrading_Partner_ID = t.iTrading_Partner_ID
>	JOIN Product p ON p.sProduct_CD = t.sProduct_CD
>
>

That didn't works just because NetAmount column didn't exists till recordset is fully generated. You can't do anything with column that didn't exists, isn't it? :-)
That's why you have to repeat calculation one more time or use Derived table as Naomi already suggested.