how to indicate query term not found using PHP serverbehaviors

i'm trying to use Dreamweaver server behaviors to do a MySQL lookup in a PHP
environment, and want to be able to indicate to the user that their search term
wasn't found. I have a form that they fill out, and can use the foundcount
server behavior to determine if the query data they enter matches any records
in the database (that works fine, as does retrieving the data if there is a
match). But on my form I want the return info fields to be unpopulated until
they enter an order number and I do the search. If there's a match, i return
the data, but if there's no match, I want to return a message saying that.
Problem is that since the PHP code that includes the form is the action, if I
try to set a flag to either enable or disable a default condition (no error
message) that set to then display a "order number not found" message, the flag
will get reset when the form action is run. I have to believe this type of
error reporting is common, so would expect Dreamweaver to have this capability.
Am I missing something? Thanks.

You say you have a record set if there are records. Just do a
conditional record set that if records, user sees records, else a
message that no records were found.