Solved

Delphi 7 :: TADOQuery OnAfterScroll Error with parameters

Posted on 2007-11-27
12
1,203 Views
Last Modified: 2013-11-23
Dear Experts,

I have 2 TDBGrid components.
The 1st one must display master table records and the second one displays detail table records
for the selected row in the master table.
qOrders = Master Query
qParts = Detail Query.

On qOrders' OnAfterScroll event I have the following code:
**** PS: See code snippet.

When my application starts up I receives and error:
"EDatabaseError with message 'qParts: Parameter 'POrderNumber' not found'...."
This parameter does exist and when I click the error message away the application starts up and
when scrolling through the master dbgrid the code is working 100%. It is only when the app starts up when I receive this error. After that, it is working as expected.

What can possible be wrong?

Please help.
procedure TPickingListFrame.qOrdersAfterScroll(DataSet: TDataSet);

begin

  inherited;

  If qOrders.IsEmpty then Exit;
 

  qParts.Close;

  qParts.SQL.Clear;

  qParts.SQL.Text := 'SELECT POrderNumber, ItemNumber, ItemDescription, Qty FROM tblCallOff WHERE '+

    '(POrderNumber = :POrderNumber) AND (Deleted = :Deleted) ORDER BY ItemNumber';

  qParts.Parameters.ParamByName('POrderNumber').Value := qOrders.FieldByName('POrderNumber').AsString;

  qParts.Parameters.ParamByName('Deleted').Value := 0;

  qParts.Open;

end;

Open in new window

0
Comment
Question by:Marius0188
  • 3
  • 3
  • 2
  • +2
12 Comments
 
LVL 27

Expert Comment

by:kretzschmar
ID: 20363690
ensure, that the ParamCheck-property of the TAdoQuery is set to true

meikl ;-)
0
 
LVL 27

Expert Comment

by:kretzschmar
ID: 20363698
in case that the sql don't change during runtime (except the parameterValues),
you could simple close, set the parameter and open again
(a clear and new set of the sql is not needed then)
(would be also raise the performance)

meikl ;-)
0
 
LVL 4

Expert Comment

by:JeePeeTee
ID: 20363862
Is your DBConnection and your qOrders/qPart opened at designtime? Close them before you launch you application.
0
 
LVL 10

Expert Comment

by:dinilud
ID: 20363906
are you sure the error from "qOrdersAfterScroll" event
0
 
LVL 10

Expert Comment

by:dinilud
ID: 20363970
Change component creation order of these two components.
(qOrders,qParts)
0
Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

 
LVL 10

Expert Comment

by:dinilud
ID: 20363998
Set Active property of qOrders equal to false. then open this dataset in the "formcreate" event.




procedure TPickingListFrame.FormCreate(Sender: TObject);
begin
   qOrders.Open;
end;
0
 
LVL 4

Expert Comment

by:JeePeeTee
ID: 20364018
Don't open on TPickingListFrame.FormCreate(Sender: TObject). Open during TPickingListFrame.FormShow(....

This will by-pass creation order issues as well.
0
 
LVL 21

Accepted Solution

by:
developmentguru earned 500 total points
ID: 20365253
With my own testing I verified your results.  I also discovered that having an active TADOConnection (referenced by the ADOQuery) corrected the situation.

Let me know if you need more.
0
 
LVL 27

Expert Comment

by:kretzschmar
ID: 20617343
as the questioner itself didn't response to any comment which wass done, so that any advice due lack of feedback could be/ could not be right, i would recommend to delete this question

meikl ;-)
0
 
LVL 1

Expert Comment

by:Computer101
ID: 21197650
Forced accept.

Computer101
EE Admin
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Introduction The parallel port is a very commonly known port, it was widely used to connect a printer to the PC, if you look at the back of your computer, for those who don't have newer computers, there will be a port with 25 pins and a small print…
Have you ever had your Delphi form/application just hanging while waiting for data to load? This is the article to read if you want to learn some things about adding threads for data loading in the background. First, I'll setup a general applica…
Along with being a a promotional video for my three-day Annielytics Dashboard Seminor, this Micro Tutorial is an intro to Google Analytics API data.
Windows 10 is mostly good. However the one thing that annoys me is how many clicks you have to do to dial a VPN connection. You have to go to settings from the start menu, (2 clicks), Network and Internet (1 click), Click VPN (another click) then fi…

864 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

25 Experts available now in Live!

Get 1:1 Help Now