A question on timing with data preparation

rbuser

Hi there:

I am using DBISAM in a project for my client which makes heavy use of the RB
environment for reporting. DBISAM does not provide for views in the sense
that (for example) MS SQL, Access or ORACLE might. I need to make a fairly
complicated set of SQL joins in a script which runs using an ExecSQL
statement and creates/updates several tables on the fly. Following this I
can then run the report which assumes the presence and population of these
tables.

I therefore run this script in the application code prior to calling the
templated report and this is OK; however on a subsequent call to the
application method I get a DBISAM error telling me that the table is still
in use even though the report has been closed and the original script has
long been run.

I would therefore like to be able to run this query from within the
reporting environment so that the data is forst created then the report
template is loaded and the report can be previewed, printed and archived.

Is there a point in time where I can call back on the SQL script which runs
this from within the reporting environment - a sort of OnBeforeDataCreation
event? here is the basic pseudocode

Begin
Create DBISAMQuery;
try
Load SQL from external table; // complicated set of joins and table
creation
ExecSQL; // this creates and populates the tables required by the report
template
finally
Free DBISAMQuery;
end;
LoadTemplateName;
PrintReport;
end;

DBISAM can also create in-memory tables. Is there any way in which I can
direct the DADE data module in the report explorer to access these in-memory
tables instead of physical ones since they are in all other aspects exactly
the same?

Please let me know if there is any more expanded information I can supply -
thanks in advance for any help,

David Mustard

rbuser

Sorry. Why do I always forget to mention the most important point! :=))

RB Enterprise version 10.2 and I have the DBISAM DADE plug-in working fine
under the latest version of DBISAM (4.23) all under Delphi 2006.

nardmoseley

- you can use the Report.OnInitializeParameters and
Report.BeforeOpenDataPipelines events to create/initialize parameters, and
to prepare data, modify SQL, etc.

- After you run the report try calling.

myReport.Print;

myReport.Template.New; // clear the layout
myRport.FreeModules; // free the datamodule and code module

- You can use TdaSQLBuilder to modify the sql assoicated with a dataview.
See TdaSQLBuilder in the RBuilder.hlp

- Another option is to create a custom dataview class. For an example, see
RBuilder\Demos\EndUser\Custom Dataviews.

rbuser

Thanks Nard,

I have also been experimenting with the creation of a custom data view class
template on the query to see if that coughs up something useful for the
future (based on your daADOTemplateDataView examples which I found lurking
in the newsgroup).

This way I can hopefully create a daDBISAMTemplateDataView unit from which I
can create a set of template views and see if these help. The advantage
being that the contents of these views are less likely to be creatively
intercepted by the user but will give them the chance to create a report
from the data without worrying about how it is made up. On top of that it
reduces the need to create pass-through code which I'm trying to avoid.

It's slow work but the first run went OK although it reported a stack
overflow error so I need to go over the code carefully and see what I've
forgotten to address. If it all works after general tweaking and so on
maybe it might be something which other DBISAM users can make use of?

cheers - David.

nardmoseley

Yes. Please email any examples to support@digital-metaphors.com and we can
make them available to other DBISAM users.