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Q237388: PRB: 32-Bit ODBC Drivers Can’t Be Used from 16-Bit Applications

Article: Q237388
Product(s): Windows for Workgroups and Windows NT Networking Issues
Version(s): 1.5,2.0,2.1,2.5,2.6
Operating System(s): 
Keyword(s): kbDatabase kbMDAC kbVC kbOSWin95 kbGrpDSVCDB kbGrpDSMDAC kbDSupport
Last Modified: 23-AUG-2001

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The information in this article applies to:

- the operating system: Microsoft Windows 98 
- Microsoft Data Access Components versions 1.5, 2.0, 2.1, 2.5, 2.6 
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SYMPTOMS
========

The Microsoft 32-bit ODBC drivers fail when called from a 16-bit application
through the ODBC thunking layer. Particularly under Windows 95 and Windows 98,
you will not be able to connect without the application failing.


CAUSE
=====

The Microsoft 32-bit ODBC drivers were not designed or tested to be used from
16-bit applications. Furthermore, drivers, such as the Access and SQL server
drivers, create multiple threads, which thunking in Windows 95 and Windows 98
doesn't support.

RESOLUTION
==========

If you need to access databases using the newer 32-bit ODBC drivers from a
16-bit application, you cannot do it directly. You will need to take the
database access portion out of the 16-bit application. Build a brand new 32-bit
application that will perform the database access. Then you can re-code your
16-bit application to use interprocess communication such as Sockets, DDE, and
OLE Automation in order to transfer data to and from new 32-bit application.

As it might turn out to be too much work, perform the above steps only if you
have huge 16-bit application and data access is only a small part of it. If you
have a smaller 16-bit application, it is best to reprogram and rebuild the
application with the 32-bit version of Visual C++.
The 16-bit SQL Server ODBC driver, which is included with SQL Server 6.5 can be
used against SQL Server 7.0, although you will have some limitations, such not
being able to use the new SQL 7.0 data types.

STATUS
======

This behavior is by design.

Additional query words:

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Keywords          : kbDatabase kbMDAC kbVC kbOSWin95 kbGrpDSVCDB kbGrpDSMDAC kbDSupport 
Technology        : kbOSWin98 kbAudDeveloper kbOSWinSearch kbMDACSearch kbMDAC150 kbMDAC200 kbMDAC210 kbMDAC250 kbMDAC260
Version           : :1.5,2.0,2.1,2.5,2.6
Issue type        : kbprb

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