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Excesive calc events?

edited October 2006 in General
I'm using RB 10.4 with dbisam 4.24.1. I have a tppvariable in the detail section of a report and it
seems to be firing the oncalc event an additional time at the top of the next page. What could
cause this? It's a simple single column report.

Thanks



--- posted by geoForum on http://delphi.newswhat.com

Comments

  • edited October 2006
    Hello,

    In our testing, the OnCalc event is firing as designed. Take a look at the
    following article on making calculations using the TppVariable component and
    see if perhaps it can guide you in the right direction.

    ----------------------------------------------------------------------
    TECH TIP: Performing Calculations
    ----------------------------------------------------------------------

    Calculations can be done either on the data access side or within
    ReportBuilder.

    When designing reports there are always decisions to be made as to how much
    processing to do on the data side versus the report side. Usually doing more
    on one side can greatly simplify the other. So it is often a personal choice
    based on the power and flexibility of the data and report tools being used.


    DataAccess
    ----------

    a. Use SQL - using SQL you can perform many common calculations:

    example: Select FirstName + ' ' + LastName As FullName,
    Quantity * Price AS Cost,


    b. Delphi TDataSets enable you to create a calculated TField object and use
    the DataSet.OnCalcFields event

    c. Perform any amount of data processing, summarizing, massaging etc. to
    build a result set (query or temp table) to feed to the report.


    ReportBuilder
    -------------

    Calculations in ReportBuilder are performed primarily using the TppVariable
    component.

    a. Set the Variable.DataType

    b. Code the calculations using the Variable.OnCalc event.

    c. Use the Timing dialog to control the timing of the OnCalc event. To
    access the Timing dialog, right click over the Variable component and select
    the Timing... option from the speed menu.

    d. Set the LookAhead property to True, when you need to display summary
    calculations in the title, header, group header, etc.

    e. To perform calculations based on the results of other calculations use
    the Calc Order dialog of the band. To access the Calc Order dialog, right
    click over the Band component and select the Calc Order... option from the
    speed menu.


    By using TppVariable components ReportBuilder will take care of caching
    intermediate results of accumlated calcs that cross pages.

    There are a number of calculation examples in the main demos.dpr project.

    ---

    Additional Notes:

    1. Do NOT use Band.BeforePrint or Band.AfterPrint. These events fire
    multiple times and therefore should not be used for calculations.

    2. Do NOT store results in variables that exist outside of the reports. For
    example - form level variables.


    --
    Regards,

    Nico Cizik
    Digital Metaphors
    http://www.digital-metaphors.com

    Best Regards,

    Nico Cizik
    Digital Metaphors
    http://www.digital-metaphors.com
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