I have a sql like this

select m.ID, m."Expense", m."SubExpense", (d."TotalAmount" *
(1-(d."Discount"*0.01)) * (1-(d."Discount2"*0.01)) *
(1-(d."Discount3"*0.01)) - d."Less" - d."Adjustment") as "GrandTotal"
from "expensesubtype" m left join "invoice" d on m.ID = d."ExpenseCategory"

What happen is if I have no record in the invoice table that mathes in
the expensesubtype the "GrandTotal" is null. How do I replace the null
with zero? Iam trying to avoid using SP

Thanks

James