NexusDB Thread Example

I have been working several days trying to write a test program using
TThread and NexusDB. I am using C++ Builder 6. I am so confused that I am
not sure I can ask an intelligent question. I am trying to use a customer
class (not a TForm) and a TThread class. I need to TThread to make an sql
query to the database then make the query available to the customer class.
This customer class will then retrieve the data from the query and update a
customer form (TForm ) if necessary or provide customer data to other
classes.

I think I understand how to use Synchronize to update and existing TForm.
However, I cannot determine how to update a class which has been created
dynamically.

I am not asking someone to write the code for me, I am just hoping someone
has a simple example from which I can build on. I can read a little pascal
so a Delphi example will be also be welcomed.

Thanks in advance for your help.

Before I run off in the wrong direction, might I ask what type of problem
you are trying to solve by using a TThread?

--


Eivind Bakkestuen [NDD]
Please, no email unless requested.
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"William E. Mahaffey" <wmahaffeyREMOVECAPS@PLEASEsuziessoftware.com> wrote
in message news:3f6890c1@wic040d....
> I have been working several days trying to write a test program using
> TThread and NexusDB. I am using C++ Builder 6. I am so confused that I
am

Eivind,

I have a multi-user Job Tracking program that I wrote about 3 years ago
using FlashFiler. To make a long story short I need to upgrade it and move
to NexusDB. One of the user requests is to allow multiple copies of
different modules to run simultaneously. For instance the user may need to
look at multiple customer records and/or multiple job records and/or
multiple inventory records at the same time. This means that I will have to
provide the capability of multiple customer, job and inventory forms to be
displayed at the same time. The open jobs may not be for the same customers
that are open. My Idea about how to handle that would be to design
customer, job and inventory classes that were independent of the forms and
let each customer, job or inventory session have it's own thread to access
the database.

Do I need threads here, or can I just dynamically create a session,
database, table and query for each class that I create.

Thanks so very much for your help.

William

> Do I need threads here, or can I just dynamically create a session,
database, table and query for each class that I create.

Threads are not really necessary to solve this problem. Just create the
components dynamically for the different views.

Terry

"William E. Mahaffey" <wmahaffeyREMOVECAPS@PLEASEsuziessoftware.com> wrote
in <3f689b63@wic040d.>:

> Do I need threads here, or can I just dynamically create a session,
> database, table and query for each class that I create.
>

Drop your session and table components on the form. Then simply create the
form in code using:

Application->CreateForm(__classid(TMyForm), &AFormPointer);

Since the component are on the form. Each form will work independently from
each other.

Don't forget to remove it from the active form in project option-> Forms

Also I would recommend that you create a TList to keep track of the form
(pointers) you created at runtime so you can destroy them gracefully when
you exit the program. Or simplier than that code your OnClose event to call
Delete this; so that when the user close the form it's deleted

Best Luck

--
Regards from Quebec.

David Charron

David and Terry,

Thank you so very much for your help.

William

If you use the method describe of cleaning up your form by calling "Delete
this" you will end up having problems as it will free the memory for the
form as soon as it is called. A better way to is to call the Release() ;
method of the form which allows the proper processing to take place.

From the Help:

Description

Use Release to destroy the form and free its associated memory.

Release does not destroy the form until all event handlers of the form and
event handlers of components on the form have finished executing. Release
also guarantees that all messages in the form's event queue are processed
before the form is released. Any event handlers for the form or its children
should use Release. Failing to do so can cause a memory access error.

Note: Release returns immediately to the caller. It does not wait for the
form to be freed before returning.

"William E. Mahaffey" <wmahaffeyREMOVECAPS@PLEASEsuziessoftware.com> wrote
in message news:3f68a99f@wic040d....
> David and Terry,
>
> Thank you so very much for your help.
>
> William
>
>

Also another method is to set the CloseAction parameter on the OnClose event
of a form.

Simply put in the line:

Action = caFree ;

"William E. Mahaffey" <wmahaffeyREMOVECAPS@PLEASEsuziessoftware.com> wrote
in message news:3f68a99f@wic040d....
> David and Terry,
>
> Thank you so very much for your help.
>
> William
>
>

William,

Just a shot in the dark...Is it possible to use memory tables?
The user's interface speed would be incredible even with many different
customer accounts open simultaneously!
John

William E. Mahaffey wrote:

> David and Terry,
>
> Thank you so very much for your help.
>
> William
>
>
>