>> 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

>---------------------------------------------------------------------
>Joe Geiser
>CSI Business Solutions
>140 Bristol-Oxford Valley Road
>Suite 102
>Langhorne, PA 19047-3083, USA
>Phone: +1 (215) 945-8100/Fax: +1 (215) 943-8408
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>---------------------------------------------------------------------

Hi,

<PLUG>

It was specifically for the above reason that the UNIQUE key feature was
added to the LINKWAY ODBC driver.

The dictionary feature allows for the nomination of those fields in the
dataset which can uniquely define every entry in that dataset. If a value
is supplied for those fields defined as the key then only ONE entry must be
returned for that query.

Additionally LINKWAY offers a psuedo column which resolves as the TID()
function. This column will be used by such clients as Microsoft Query if
there is are no UNIQUE key but you are in the hands of the application
supporting this type of SPECIAL COLUMN.



Ken Vickers

Manager LINKWAY Development and Support
Computing Solutions Limited

TEL +44 (0) 1905 794400
FAX +44 (0) 1905 794464