SAMPLE: DAOTable Uses DAO Classes to Create Database Objects

• The Microsoft Foundation Classes (MFC) included with: - Microsoft Visual C++, 32-bit Edition, versions 4.0, 4.1, 4.2 4.2b, 5.0

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

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;

   m_FI.m_bAllowZeroLength = FALSE;

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

How to Obtain Daotbl.exe

The following file is available for download from the Microsoft Software Library:

 ~ Daotbl.exe (size: 79807 bytes) 

   ARTICLE-ID: Q119591
   TITLE     : How to Obtain Microsoft Support Files from Online Services

MORE INFORMATION

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

DAOTABLE.CPP         - APPLICATION - main application objects

DAOTDLG.CPP          - USER INTERFACE - main dialog

DATABASE.CPP         - MFC DAO - database specific functions

ADDIXDLG.CPP         - USER INTERFACE - add indexes dialog

ADDTBDLG.CPP         - USER INTERFACE - table definition dialog

FIELD.CPP            - MFC DAO - field specific functions

LISTCTRL.CPP         - USER INTERFACE - derived CListCtrl class

INDEX.CPP            - MFC DAO - index specific functions

QUERYDEF.CPP         - MFC DAO - querydef specific functions

TABLEDEF.CPP         - MFC DAO - tabledef specific functions

ADDDBDLG.CPP         - USER INTERFACE - database definition dialog

REFERENCES