On Wednesday, June 25, 1997 11:26 AM, Friedrich Harasleben
[SMTP:[log in to unmask]] wrote:
> Hi there,
>
> for those of you how might be interested. Sometimes ago there was a
> mail
> on this list by Herbert Baumgartner, how wanted to know if somebody
> has
> done successful updates on an IMAGE/SQL database from EXCEL.
>
> Yes, it works. Altough it is not very fast it does what one expects
> it to
> do (even with the standard HP ODBC driver).
>
> Cheers,
>
> Friedrich

Friedrich,

No matter where the data source comes from (an Excel spreadsheet, a
Visual "x" program - "x" can be "Basic", "C++", etc. etc. etc...) -
the one key to updating an Image/SQL dataset is a Unique, Primary
Key.

The Unique Primary Key ensures that one and only one row can be
retrieved for subsequent update, or a unique key exists for a new
entry to the datasets.  For multi-row updates or inserts, especially
if a CURSOR is used, again, it ensures that one row in the cursor can
be discerned from others.  BULK UPDATEs and BULK INSERTs rely on this
primary key as well.

The Unique Primary Key is absolutely essential if using Linked Tables
within MS Access or MS Excel - updates will not work correctly
without it and in most case, will produce a runtime error.

Lastly - even if a Unique Primary Key is used - the use of PCAPI for
the ODBC driver for updates can be iffy.  PCAPI is good at reading
the data and writing new entries, but for updates, again, you have a
better chance of success if the Unique Primary Key is defined (and
declared) in the database.

Best Regards,
Joe

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Joe Geiser
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