Re: ODBC v OO4O. Any Comments?

brian_at_qns.com (Brian Towles) wrote:

>Bill Meahan <wmeahan_at_pmsb18.pms.ford.com> wrote on 29 Jun 1995
>12:19:36 GMT:
 
> [Slice, Dice, And Frappe]
 

>>What many (most?) people who use Visual Basic think of as "using ODBC,"
>>however, is using the VB Data Control or (programmatically) the VB
>>"Data Access Objects" (CreateDyanaset, etc). These objects are built
>>on top of the MS Access "Jet engine" (really just MS Access without the
>>user interface) which, in turn, uses the ODBC API (transparently) to
>>get to remote databases (Oracle and others).
 

>Ahhh... but if you use SQLPASSTHROUGH on your Datacontrol or Dynaset
>the JET does no manipulation and hands the SQL directly to the ODBC
>API. Without the SQLPASSTHROUGH the Jet tries to optimize the Query
>and then passes it on. The net effect of the SQLPASSTHROUGH is to
>turn off the Jet Engine and merly use it as a object which will make
>all the nessesary ODBC calls for you.
 

>But there are some drawbacks. You can't really use the returned
>dynaset to update the backend oracle table (Yes you can do it if the
>dynaset contains the primary key to the table and the table has a
>primary key..but it is slower then using executable SQL (UPDATE,
>INSERT, etc) to manipulate the data and refreshing your dynaset.

Yes, but these ExecuteSQLs happen in a different, autocommited, database connection if you use JET. This really screws things up if you expect COMMIT and ROLLBACK to work.

John Fruetel
jfruetel_at_ainet.com Received on Sun Jul 02 1995 - 00:00:00 CEST