Calculations Based on Summaries

rbuser

Hi,

I have a problem similar to another posted regarding calculations, which has
to do with the variable's datatype is correct. I'm running RB 7.02 on D7Ent
and WinXP Pro. I'm also trying to do everything via the Report Explorer,
which means I must use RAP rather than Delphi events and the Object
Inspector.

I have two (DBCalcs) summary values, A and B, which appear to sum up just
fine. Then I have a variable (C) which, in its OnCalc event, is set to:
Value := (A.Value / B.Value) * 100. A and B are both of type Currency, and C
is set to dtString. The result is always 0 regardless of the two sum fields,
which is kind of explained in the response to that other posted message.

I also have other calculated fields which I added using the Calcs tab of the
dataview.

With that in mind, I have the following questions:

1. Is my statement about having to use RAP rather than Delphi events and
Object Inspector correct?
2. I couldn't find a way to change the default datatype for C within RB/RAP.
I had to save the report to an .rtm file and load it into another
(development) project so I can change the datatype in Delphi. Is it not
possible to change/set the datatype with RB/RAP?
3. Is there a way to make sure the event is firing? Can I set a breakpoint
or use a "ShowMessage" equivalent?
4. When viewing the Data tab and realizing that a calculated field was added
by mistake using its Calcs tab. Is there a way to remove that incorrect
calculated field? I tried the obvious (pressing the Del key, right-clicking,
etc. -- Right-Click and selecting Delete removes the entire dataview which
is not what I want to do).

Thanks for your help

Waguih

nicocizik

Hi Waguih,

1. Yes, RAP would be your best option if trying to use different event
handlers for each template you load in the Report Explorer.

2. You can change the datatype of a component using RAP. Select the
component in the report tree and look for the datatype property in the Code
Toolbox Objects tab in the lower right corner of the Calc Tab.

3. The ShowMessage function is allowed in RAP and is available to drag from
the Code Toolbox under the "language" tab and "utility" option. There is
also a third party debugger called CodeSite which can be used with RAP
passthu function to debug RAP code.(See the RAP demos).

4. To Remove an item from the included list of the Calcs tab in the Query
Designer, just double click it.

--

rbuser

Hi Nico,

Thanks for your response. Re item #4, I don't know how I could've missed
trying to double-click. However, re item #2, I did find my way there, but
then all these properties appear to be read-only. I even tried
double-clicking that. I also tried setting the DataType property in the
OnCalc event handler, e.g. DataType := dtDouble. The RAP compiler, however,
complained. Can you please shed some light on this for me?

Thanks

Waguih

nicocizik

Hi Waguih,

Try setting the variable's datatype in the GlobalOnCreate event. You can
access this event by right clicking in the Report Objects window of the Data
tab in the Report Designer and selecting "Module". Then select the Events
option and create a new OnCreate event. Insert code that looks something
like the following into this event...

procedure GlobalOnCreate
begin
Variable1.DataType := dtDouble;
end;

Now you can use the variable as a double in it's OnCalc event. Don't try
changing the datatype as the report is generating. Use separate variables
if you would like to use different datatypes.

--

rbuser

Thanks Nico. This worked very well. I suspect I also have to set the
DisplayFormat there too after setting the DataType.

Cheers,

Waguih

rbuser

Where/when is the other post that explains how to do a calc based on summary
values? I am trying to do the same and get a value of 0 everytime. (The
report is pretty simple, each row is selected from a stored procedure that
sends back each field needed for the row. The report is not grouped and I
have a summary band with a number of dbCalc objects that are simple
summaries of the corresponding fields in the report. I need to do (A/B) *
100 for two of these columns. This needs to be done with RAP.)

TIA,
Carolyn

digitalmetaphors

The easiest way to do it from RAP is to add a calculated field on your
dataset that is the total. Then you can simply reference that field from the
pipeline in the RAP OnCalc event handler of a TppVariable component.

Otherwise, here is an example of doing it in RAP without a calc field:

http://www.digital-metaphors.com/tips/MDRapRunningTotalInFooter.zip

Cheers,

Jim Bennett
Digital Metaphors

rbuser

Thanks for your reply. I have not looked at the example yet because I would
like to understand the "easiest way" first. I am fairly new to Delphi and
Report Builder (like what a see and know so far) so here are some (probably)
simple level questions I have.

Each row of my report is a summary of how much money was billed against a
given contract, how much was paid out, and some other similar fields. I
have a header, detail, footer, and summary band in the report. In the
Summary band I used dbCalc fields to sum the various columns. So I have a
field called Total Billed and another called TotalPaid. I need the
percentage paid. In the same summary band I have tried to put in a
tppVariable and in its OnCalc event (on ReportEnd) I tried value :=
(TotalPaid.fieldValue / TotalBilled.fieldValue)/ 100; and I get 0. I even
tried value := 3.5; to see if it would display anything and that shows 0
also.

When you say to add a calculated field on the dataset that is the total, do
you mean I should add it to the stored procedure and keep a running total
there of the two values and pass those back each time I get a new row? If
so, how do I reference just the last totals to calculate my percentage?

Thanks,
Carolyn

digitalmetaphors

On your variable, set its DataType to double, as it defaults to string and
will show a zero in this case.

Also, in order to assure that the OnCalc events fire in the right order, use
TppVariable instead of TppDBCalc. Set the variable's CalcOrder property so
you can be 100% sure that the calcs fire in the right order. This only
applies to the variables in the same band.

It is problably better to not add calc fields to the stored proc, but rather
calculate them in the first pass with report event handlers.

Cheers,

Jim Bennett
Digital Metaphors

rbuser

Thanks, for some reason I could not connect to this NG last week so I just
saw your response. I'll try it today or tomorrow and let you know if I have
any remaining questions.

Thanks,
Carolyn

rbuser

OK please be patient with these elementary questions, but I have not really
found anything in the tutorials or examples yet that have gotten me past
this point yet.

I added a variable in my summary band and put the following in it's onCalc
method:

Value := Value + dbpContractBalance['O_TOTAL_BILLED'];

It works as I would hope and comes up with the same answer as when I used a
dbCalc variable set to show the sum of the Total Billed field. I then tried
putting another variable in that would eventually show the (total amount
billed - total pending - total paid) / total paid. I thought I would first
try to reference my calculated variable by just entering:

Value := vTotalBilled;

Where vTotalBilled is the variable I calculate above. I tried setting it as
a Double and Currency (my calculated variable is Currency) and verified the
calc order so that vTotalBilled is calculated first. But in all cases it
just displays a 0.

What am I doing wrong? If I cannot reference another object from this one,
how do I declare another (local? global?) variable so that I can calculate
the totals in this method and then use them (for example, I will need to
calculate the total pending, billed, and spent and then use those in my
equation)? Does it have to be a global variable? Is there an example or
tutorial that would help me get a foothold on using RAP?

Thanks,

Carolyn