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Message Posted: Mon, 07 May 2001 @ 09:13:00 GMT


     
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Subj:   OLE DB and ADO
 
From:   Mats Ginman

We are seeking some advice for creating a visual Basic application to view and report data from a teradata database. We intend to use ActiveX data Objects (ADO) as the object model for our database access.

Out first question is whether a natice OLE DB driver exists for teradata? Currently we have only been able to connect using OLE DB driver for ODBC, and i suspect there may be some performance penalties in using this.

Since some of the queries may take some time to execute, we intend to employ some kind of asynchronous strategy so that a user may request some data and at some point in the future that data will be available in a data bound grid. In the meantime, they will be able still use the GUI whislt the original query is still running.

Our initial prototype uses the ADO events FetchProgress (which is fired when each row is returned from the query) and FetchComplete (which is fired when the query has finished). For these events to be fired a client side cursor has to be used with the ADO connecton event. Even in a simple example, this whole method can take quite a while to execute before the first event is fired for the first row returned. Hence the application appears in a 'hung' state whilst this is in progress - not very user friendly!

Is this a sensible method or are there better alternatives? I have seen the documentation for ASYNC command with embedded SQL, but there is a lack of clear examples for us to attempt to us it.



     
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