You can not use computed fields this way, you can only use them in derived tables. Otherwise you have to repeat the computation again.

See bellow:

>

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

>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
>
>

>
>However, this does work with the computation included in the column
>
>

>SELECT	(t.decTrade_Product_Balance / t.decTrade_Qty) * (t.decTrade_Ext_Price + t.decTrade_Shipping_Charge + t.decTrade_Other_Charge) 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
>