Query computation problem

Question

Warning: I'm a M$ Access programmer, set to putting a db into Oracle! I've been trying to put together a view that returns a value based upon a calculation. To make this calculation I have to check if one field is NULL or 0, and if the other field is 0. If so then I just want to return a hyphen (-), otherwise I want to return a calculation from the numbers.
I've tried many combinations. Here's one sample.
((DECODE(BUILD_QTY,NULL,0,0,0,1)) +
(DECODE(DEFECT_QTY,NULL,0,1))),2,
((DEFECT_QTY/BUILD_QTY) * 1000000),'-') AS PPM
When I remove this from the SELECT statement it works beautifully. It even works when I leave it with two simple DECODE statements (one for BUILD_QTY and one for DEFECT_QTY).
I've thought of creating a function to do this calculation for me outside the SELECT stmt, but that's WAY OVER MY HEAD in Oracle.
Any suggestions with what I'm doing wrong will be gratefully accepted.
Sherry

Answer 1

I think you are looking for something like:
DECODE(NVL(build_qty,0),0,'-',
       DECODE(NVL(defect_qty,0),0,'-',
              (defect_qty/build_qty)*1000000)) ppm
which in more traditional IF THEN ELSE syntax resolves to
IF build_qty = 0 OR build_qty IS NULL THEN
   RETURN '-'
ELSE
   IF defect_qty = 0 OR defect_qty IS NULL THEN
      RETURN '-'
   ELSE
      RETURN (DEFECT_QTY/BUILD_QTY) * 1000000)
   END IF
END IFThe NVL function returns its second argument if the first is NULL.
HTH
John