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Q237285: SAMPLE: Daoprop.exe Sets a Custom Property on an Access Database

Article: Q237285
Product(s): Microsoft C Compiler
Version(s): 6.0
Operating System(s): 
Keyword(s): kbfile kbSample kbDAOsearch kbVC kbVC600 kbGrpDSVCDB kbDSupport
Last Modified: 26-MAY-2002

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The information in this article applies to:

- Microsoft Visual C++, 32-bit Enterprise Edition, version 6.0 
- Microsoft Visual C++, 32-bit Professional Edition, version 6.0 
- Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
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SUMMARY
=======

The Daoprop.exe sample demonstrates how to add a custom property to a Microsoft
Access database by using the Microsoft Foundation Class Library (MFC) Data
Access Objects (DAO) classes and the underlying DAO OLE interfaces.

The sample is based on another Microsoft Knowledge Base article, which
demonstrates the same concept by using Microsoft Visual Basic for Applications
in Microsoft Access 97. For additional information, click the article number
below to view the article in the Microsoft Knowledge Base:

  Q178745 ACC: Using DAO to Set and Retrieve Custom Database Properties

The MFC DAO classes directly expose a subset of the DAO hierarchy. However, the
MFC DAO classes do not expose all of the functionality that is available to
developers who are using Microsoft Visual Basic, Visual Basic for Applications,
or the DAO Software Development Kit (SDK) in Visual C++. It is possible to use
the complete hierarchy indirectly by using the underlying DAO OLE interfaces
that the MFC DAO classes wrap.

MORE INFORMATION
================

The following file is available for download from the Microsoft Download
Center:

  Daoprop.exe

Release Date: Sept. 7, 2000

For additional information about how to download Microsoft Support files, click
the article number below to view the article in the Microsoft Knowledge Base:

  Q119591 How to Obtain Microsoft Support Files from Online Services

Microsoft used the most current virus detection software available on the date of
posting to scan this file for viruses. After it is posted, the file is housed on
secure servers that prevent any unauthorized changes to the file.

The Daoprop.exe sample contains the following files:

+---------------------------------+
| File name           | Size      | 
+---------------------------------+
| Daoproperty.asp     | 42.8 KB   | 
+---------------------------------+
| Daoproperty.clw     | 1.54 KB   | 
+---------------------------------+
| Daoproperty.cpp     | 3.34 KB   | 
+---------------------------------+
| Daoproperty.dsp     | 4.42 KB   | 
+---------------------------------+
| Daoproperty.dsw     | 545 bytes | 
+---------------------------------+
| Daoproperty.h       | 1.23 KB   | 
+---------------------------------+
| Daoproperty.ncb     | 57.0 KB   | 
+---------------------------------+
| Daoproperty.opt     | 47.5 KB   | 
+---------------------------------+
| Daoproperty.rc      | 9.74 KB   | 
+---------------------------------+
| Daopropertydoc.cpp  | 9.25 KB   | 
+---------------------------------+
| Daopropertydoc.h    | 1.68 KB   | 
+---------------------------------+
| Daopropertyview.cpp | 1.67 KB   | 
+---------------------------------+
| Daopropertyview.h   | 1.61 KB   | 
+---------------------------------+
| Db1.mdb             | 58.0 KB   | 
+---------------------------------+
| Mainfrm.cpp         | 1.70 KB   | 
+---------------------------------+
| Mainfrm.h           | 1.37 KB   | 
+---------------------------------+
| Resource.h          | 739 bytes | 
+---------------------------------+
| Stdafx.cpp          | 213 bytes | 
+---------------------------------+
| Stdafx.h            | 1.19 KB   | 
+---------------------------------+
| Daoproperty.ico     | 1.05 KB   | 
+---------------------------------+
| Daoproperty.rc2     | 403 bytes | 
+---------------------------------+
| Daopropertydoc.ico  | 1.05 KB   | 
+---------------------------------+

The DAO interfaces are defined in the Dbdaoint.h file in the VC98\Include folder.
When you use the DAO OLE interfaces, it is often necessary to use the VARIANT
and BSTR data types. These data types can be conveniently manipulated by using
the wrapper class COleVariant. To initialize a VARIANT object with a BSTR
string, use the VT_BSTRT type specified to ensure that the string is created as
an ANSI string in ANSI builds, and as a Unicode string in Unicode builds. For
additional information about strings and DAO, click the article number below to
view the article in the Microsoft Knowledge Base:

  Q140599 PRB: MFC DAO Functions Accepting COleVariant Strings May Fail

For a demonstration of how to initialize a COleVariant object and extract values
from it, see the DAOVIEW sample in the Microsoft Developer Network (MSDN).

The project included in the self-extracting executable is an MFC single document
project. Its functionality is contained in the three menu handlers
OnPropertyCreate, OnPropertyGet, and OnPropertySet. These functions call the
CreateCustomProp, GetCustomProp, and SetCustomProp functions, respectively.

Several concepts are demonstrated by this sample:

- Creating a COleVariant of type VT_BSTRT in OnPropertyCreate and
  OnPropertyGet.

- Using the V_BSTRT macro to extract a string from a COleVariant in
  OnPropertyGet.

- Using the DAO OLE interfaces in CreateCustomProp, GetCustomProp, and
  SetCustomProp.

- Using the DAO_CHECK macro to test the success of a DAO call and throw an
  exception in case of failure.

- Using the TRY, CATCH_ALL, END_CATCH_ALL and THROW_LAST macros to correctly
  handle exceptions when using the DAO OLE interfaces.

To check the custom property in your Access database file, open the file in
Access 97, on the File menu, click Database Properties, and then click the
Custom tab.

REFERENCES
==========

For additional information about using DAO functions, click the article numbers
below to view the articles in the Microsoft Knowledge Base:

  Q178745 ACC: Using DAO to Set and Retrieve Custom Database Properties

  Q140599 PRB: MFC DAO Functions Accepting COleVariant Strings May Fail

For more information, please see the DAOVIEW sample, which is located on the
Microsoft Developer Network (MSDN) Web Workshop:

  http://msdn.microsoft.com/library/devprods/vs6/visualc/vcsample/_sample_mfc_daoview.htm
  (http://msdn.microsoft.com/library/devprods/vs6/visualc/vcsample/_sample_mfc_daoview.htm)

For a description of how to use the DAO OLE interfaces, see the MFC technical
note #54 in the MSDN.

Additional query words: Daoprop

======================================================================
Keywords          : kbfile kbSample kbDAOsearch kbVC kbVC600 kbGrpDSVCDB kbDSupport 
Component         : dao
Technology        : kbVCsearch kbAudDeveloper kbVC600 kbVC32bitSearch
Version           : :6.0
Issue type        : kbhowto

=============================================================================

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