Re: Modifying structure file

Don - the recursive link  is really very, very neat and efficient. Once you get the hang of it you'll never go back.


Don (Friedman)
Pittsburgh

On 4/16/07, Don Codling <dcodling-14v5w08BjUxgXqCxlHED+A@xxxxxxxxxxxxxxxx> wrote:

April 16, 2007

Thanks Brian.

I was all set to miss the problem with auto increment fields. I shall
have to explore the alternative.

Don Codling
WP 12.0.0.602
DP 2.6x
Windows XP home, SP2
512 MBytes RAM

Brian Hancock wrote:
> Hi,
>
> The STR file can be modified and program updates distributed via a
> portable "STR" within certain boundaries.
>
> You cannot make a change to the STR which would change the layout of
> the data files, ie the tables, so anything which adds, removes or
> changes the Field Format on a panel, should not be done using the
> portable STR. If you need to change these then you need to export the
> data out when the changes is made and reimport after the change.
>
> If you use :I incrementing number fields then updating an STR will be
> a problem, as the STR file holds the value for the next record. If you
> want your application to have a "portable" STR then you need to
> replace all the :I field, with a technique described in Ralph Alvy'
> book about using Recursive Panel Links for producing an incrementing
> number... (The concept is simple you link a panel back to itself, and
> by using a reversed index, when traversing the link you arrive at the
> highest used incrementing number, you can add back your increment
> using a formula through that link to increment the counter for the
> newly created record).  As an aside, using the recursive link for
> numbering give a lot more flexibility, as you can choose the increment
> or decrement value, or you can create complex incrementing number
> patterns which can include alpha characters. One which I use alot is
> an incrementing number with a generated check digit, so I might have a
> sequece 0016, 0021, 0037,0049 where  first 3 digits are the
> incrementing number and the the final digit is a check digit
>
> On the other hand you can use a "portable" STR to change field
> formulae, link definitions, reports, colours, etc. If you change an
> index, then you need to "bed" the new STR in by starting it with an
> Index all (the easiest way to do that, is as soon as you have updated
> the STR, start the updated application with the /IND startup switch.
>
> For the web application work I am now doing with DP, most of the
> application logic is in reports, and changing reports with a portable
> STR is a piece of cake, providing you do not have :I incrementing
> number fields.
>
> I saw a complaint that DP forces you to empty data from the database
> before you can make a change to the data structure, with the
> implication that other products do not work that way. I think that
> most products do empty the data first, it is just that the application
> interfaces usually do that step for you without you knowing, by
> creating a copy of the new structure and then copying the old records
> back into the new one, then deleting the old and renaming the new.
> There are very few database management systems which permit a totally
> on-the-fly change to the data structures, and I think they all need
> exclusive access by the definer for that time that the conversion is
> taking place.
>
> Regards
> Brian
>
>
>
>
> ----- Original Message ----- From: "Don Codling"
> <dcodling-14v5w08BjUxgXqCxlHED+A@xxxxxxxxxxxxxxxx>
> To: "Dataperfect Users Discussion Group" < dataperf-Ii8YPGKeNuMyuW1uK6fEew@xxxxxxxxxxxxxxxx>
> Sent: Monday, April 16, 2007 11:13 AM
> Subject: Re: [Dataperf] Modifying structure file
>
>
>> April 15, 2007
>>
>> Thank you all. I see I can't change indexes, but the other things I'm
>> interested in can be done without a problem. I appreciate the help.
>>
>> Don Codling
>> WP 12.0.0.602
>> DP 2.6x
>> Windows XP home, SP2
>> 512 MBytes RAM
>>
>> Bill Richardson wrote:
>>> ** Reply to note from Don Codling < dcodling-14v5w08BjUxgXqCxlHED+A@xxxxxxxxxxxxxxxx> Sun, 15
>>> Apr 2007 20:53:58 -0300
>>> | Can I make those kinds of changes in a client's database by giving
>>> the
>>> | client a modified Structure (.str) file to replace the existing one?
>>> | That is, can I make the changes on a copy of the database on my
>>> | computer, & simply replace that one file in the client's database? Or
>>> | is it necessary to replace all of the client's files even for such
>>> | changes? | | If I can just change the structure file, I can add
>>> reports, change
>>> | colours, etc, for a client, without interrupting his use of his
>>> | database & its data.
>>> Check out Mastering DataPerfect, pages 418 and following. It's not a
>>> simple answer.
>>>
>>> Bill
>>>
>>>
>>>
>>> --------------------------------------------
>>> * Wm. W. Richardson                        *
>>> * Phone: 903/893-0506                      *
>>> *   FAX: 903/893-7890                      *
>>> * Running at Warp speed under OS/2         *
>>> --------------------------------------------
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-- 
Don Friedman
ProfessionalRecords.Com LLC
PRS Data Systems
205 S Main Street
Pittsburgh, PA   15215
412-784-1600 - 1-800-PRS-FILE 
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