Is there anyway to have an IF statement?

[harpal]

The dcode() function is good only if you have predefined values to check against, it can't help in range comparisions.
What you need is a UNION to join two SQL statements like this:

SELECT item, description, qty as wk_name
FROM orders
where orderdate between A and B
UNION
SELECT item, description, 0 as wk_name
FROM orders
where orderdate not between A and B
;

Hope this helps.