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Q141717: DAOTable Uses DAO Classes to Create Database Objects

Article: Q141717
Product(s): Microsoft C Compiler
Version(s): winnt:4.0,4.1,4.2 4.2b,5.0,6.0
Operating System(s): 
Keyword(s): kbcode kbfile kbsample kbusage kbDAOsearch kbDatabase kbMFC kbVC kbVC400 kbVC410 kbVC42
Last Modified: 06-MAY-2001

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The information in this article applies to:

- The Microsoft Foundation Classes (MFC), used with:
   - Microsoft Visual C++, 32-bit Editions, versions 4.0, 4.1 
   - Microsoft Visual C++, 32-bit Enterprise Edition, version 4.2 
   - Microsoft Visual C++, 32-bit Professional Edition, version 4.2 
   - Microsoft Visual C++, 32-bit Enterprise Edition, version 4.2b 
   - Microsoft Visual C++, 32-bit Professional Edition, version 4.2b 
   - Microsoft Visual C++, 32-bit Enterprise Edition, version 5.0 
   - Microsoft Visual C++, 32-bit Professional Edition, version 5.0 
   - 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 DAOTable sample (Daotbl.exe) demonstrates how to use the MFC DAO classes to
create the following common database objects: databases, tables, queries,
fields, and indexes. This dialog-based application maps the properties of these
objects to controls the user can set or view. The program source code is
organized so that most database interaction is isolated from the user interface
code to ease finding examples of how to use MFC DAO.

In addition to demonstrating the use of the MFC DAO classes, this sample can be a
useful tool for creating simple Microsoft Access databases. You can create .mdb
files from scratch, create and delete tables and queries, add and delete fields
and indexes in the tables, and modify existing queries.

The following files contain the code that performs the database operations.
Additional files in the project provide the user interface and high level
database manipulation.

  QUERYDEF.CPP, .H -- functions to create and use queries
  TABLEDEF.CPP, .H -- functions to create and use tables
  FIELD.CPP, .H    -- functions to create and use fields
  INDEX.CPP, .H    -- functions to create and use indexes
  DATABASE.CPP, .H -- functions to create and use databases

To use this code and the MFC DAO classes, you must have Visual C++ 4.0 or later.

NOTE: Beginning with Visual C++ 4.1, the DAOTable sample is included with the
Visual C++ CD.

Special Note for Visual C++ 4.1 Users
-------------------------------------

The DAOTABLE sample that shipped with Visual C++ 4.1 contains a bug that will
prevent you from creating fields that are of any type other than text. To
correct this problem, you can download the fixed sample as directed below or
make the following correction to the ADDTBDLG.CPP file:

Replace this line

     m_FI.m_bAllowZeroLength = TRUE;

with this line:

     m_FI.m_bAllowZeroLength = FALSE;

This change will disable a workaround that was necessary to avoid a bug in Visual
C++ 4.0. In the download files (DAOTBL.EXE), the workaround code is
conditionally compiled depending on which version you are using to build the
sample. If you do not make the correction given in this section and you run the
application using the Visual C++ 4.1 DLLs, the following exception will be
thrown when you try to create nontext fields:

  Couldn't create field--Exception: Invalid Operation.

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

The following files are available for download from the Microsoft Download
Center:

Daotbl.exe

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. Once posted, the file is housed on secure
servers that prevent any unauthorized changes to the file.


NOTE: The file must be decompressed by typing "DAOTBL.EXE -d" to re-create the
directory structure.

The MFC DAO classes provide a way to directly use the Microsoft Jet Database
Engine. Although Visual C++ wizards automatically generate code that will create
and open recordsets for you based on implicitly created database and workspace
objects, the code they provide does not demonstrate creating and manipulating
MFC DAO objects directly. With MFC DAO classes, you can create the majority of
DAO objects and set their properties.

This sample demonstrates using the MFC DAO classes to create and use the
following DAO objects: databases, tables, queries, fields, and indexes.
Exception handling with both MFC exception macros and the C++ exception
mechanism is also shown. Further, DAO exceptions are put to use in detecting the
existence of objects in the DAO collections.

Listed below are all the files in the project (except those that are common to
all Visual C++ projects). Each file is shown with the type of components it
contains and a brief description.

  ADDQYDLG.CPP         - USER INTERFACE - query definition dialog
  ADDQYDLG.H
  DAOTABLE.CPP         - APPLICATION - main application objects
  DAOTABLE.H
  DAOTDLG.CPP          - USER INTERFACE - main dialog
  DAOTDLG.H
  DATABASE.CPP         - MFC DAO - database specific functions
  DATABASE.H
  ADDIXDLG.CPP         - USER INTERFACE - add indexes dialog
  ADDIXDLG.H
  ADDTBDLG.CPP         - USER INTERFACE - table definition dialog
  ADDTBDLG.H
  FIELD.CPP            - MFC DAO - field specific functions
  FIELD.H
  LISTCTRL.CPP         - USER INTERFACE - derived CListCtrl class
  LISTCTRL.H
  INDEX.CPP            - MFC DAO - index specific functions
  INDEX.H
  QUERYDEF.CPP         - MFC DAO - querydef specific functions
  QUERYDEF.H
  TABLEDEF.CPP         - MFC DAO - tabledef specific functions
  TABLEDEF.H
  ADDDBDLG.CPP         - USER INTERFACE - database definition dialog
  ADDDBDLG.H

REFERENCES
==========

For more information about the MFC DAO classes, please see the Visual C++ Help
file. For additional documentation on DAO, please see the help files in the DAO
SDK that is provided on the Visual C++ 4.0 CD-ROM.

Additional query words:

======================================================================
Keywords          : kbcode kbfile kbsample kbusage kbDAOsearch kbDatabase kbMFC kbVC kbVC400 kbVC410 kbVC420 kbVC500 kbVC600 
Technology        : kbAudDeveloper kbMFC
Version           : winnt:4.0,4.1,4.2 4.2b,5.0,6.0

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