in the following statement:
(SUM(d.SD_TOTAL) - SUM(d.SD_QTY*p.PR_PRICE)- SUM(d.SD_QTY * (SELECT
x.TX_AMTEA FROM PRTAXCODE x
WHERE (x.TX_CODE=d.SD_TAXCODE AND x.TX_CAT=p.PR_CAT)))) AS PRODDIF

x.TX_CAT and x.TX_CODE and x.TX_AMTEA may or may not be NULL.

If it is null, I would like to return a value of zero for the last
subSelect so that the value of this field would be the difference of
(SUM(d.SD_TOTAL) - SUM(d.SD_QTY*p.PR_PRICE) AS PRODDIF

is this possible to convert a NULL to a zero on the fly?

Dixon Epperson