Question

What is wrong with this code. I am checking whether there is an available record in the database before inserting a new serial number. When I enter any record whether available or not, it throws an error message:

“Expression is not valid”. (PowerBuilder Classic 12.5 and SQL Server
2008)

If This.GetColumnName() = "serial_No" Then
 long ll_serial
    ll_serial=dw_newrecord.find(data, 1, dw_newrecord.rowcount())
    if ll_serial>0 then
    messagebox("validation error", "The record already exists")
    return 1
end if
End If

Answer 1

It is likely that your data expression has a syntax error. It can be some misformed code -like missing quotes- or maybe that the column name is incorrect.

To help for tuning a filter or find expression, you can test it in the datawindow design screen via the Rows / filter menu.

A better solution for long-term coding design would be to integrate the Datawindow Debug Machine (made by a colleague of mine) to your project. It is a precious tool to prototype datawindow expressions for finding, filtering but also for dynamic objects creation / modification in a datawindow. And while correctly interfaced with a datawindow ancestor of your project, it can help with filters and find expression errors like here.

EDIT: As RealHowTo noticed, the tool has been updated. Here is the current latest version (but there is no updated demo screencast though).