How to use MFC DAO classes to create database objects in Visual C++

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: