Crystal reports selecting record that contain empty strings or "null"

Question

I have a report that for a field called JobNo there are some records that have "null" as the the cell value and some that have an empty string "". there is another field called AccntNo that im also selecting by in the same selection formula.

This is what i have tried without success in the selection formula for crystal reports.

{accnt.accno} = "7015" and
{accnt.jobno} = "" or {accnt.jobno} isnull

any help is apreciated

Answer 1

Selection formula doesn't work as expected, sometimes.

I suppose that this will work

{accnt.accno} = "7015" and
( isnull({accnt.JobNo}) or {accnt.jobno} = "" )

First of all I put parenthesis on 'or' clause.
But, the strangest thing, is that isnull clause must be evaluated before other comparison clauses.