PDox->Delphi; Three Questions HELP!

PDox->Delphi; Three Questions HELP!

Post by KJumo » Mon, 26 Feb 1996 04:00:00

1) There are a few free versions on Delphi Super Page, TQBE.zip I
think.For a commercial version check Woll2Woll Infopower, check Delphi
Super Page for a demo. TwwQBE if you want to use Paradox QBE as a TTable
or TQuery.

2)Paradox Val Checks do not work in Delphi, only Default fields appear.
There is a free or perhaps test version of edit field components which
support pictures on Delphi Super Page as well. I think the file name is

Delphi Super Page is http://sunsite.icm.edu.pl/~robert/delphi/

3) Autoincrement fields are generated only when the record is posted. The
only way around is to get the max of the autoincrement field + 1. Note
that this presumes that none of the previous records have  been deleted.
As a rule it is not advisable to use autoincrement fields. If the table
gets corrupted and rebuilt the original sequencing is lost. Use a separate
table with a field, read the field, update it by one. and use the value.


1. PDox->Delphi; Three Questions HELP!

Not sure of the degree to which the use of Paradox/Database Desktop (DBD)
QBE files were tested for use in Delphi (if at all), but my experience has
been that:

1. Yes, you can use them in this manner.
2. The result set will always be read-only.

Some QBE files that use odd combinations or conditions may not work, some
"playing around" would be adviseable.

Default values work, but the Picture templates do not. Minimum and Maximum
constraints (validity checks) do work, but will not fire until an attempt
is made to post a record with changes. Referential Integrity works.

No. Automatically incrementing fields -- whether the Paradox Auto-increment
or the LIBS trigger-based incrementing -- are a function of the data engine
back-end. This operation is totally outside the awareness and control of
the front-end application.

In Delphi, when you "insert" a record, the table file is not affected.
Delphi merely (speaking in general terms, here) allocates memory and
displays blank entry points/cells on screen. When an attempt to post is
made, a signal goes from the application front-end to the data back-end to
add a record to the file (more like the SQL command INSERT). It is when the
data back-end receives this signal that the incrementation fires.

So if you were to consistently use a fast sequence that does a Delphi
"insert", posts the new record (causing an incrementing), and then
immediately puts the record back into editable mode. This would look
something like:

  with Table1 do begin

Steve Koterski                  "Results! Why, man, I have gotten a lot of
Product Group Manager           results. I know several thousand things
Delphi Technical Support        that won't work."
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