Q129732: INFO: Data Access Objects Have Properties Based on Database Type

Article: Q129732
Product(s): Microsoft Visual Basic for Windows
Version(s): 
Operating System(s): 
Keyword(s): kbGrpDSVBDB
Last Modified: 11-JAN-2001

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Visual Basic Learning Edition for Windows, version 6.0 
- Microsoft Visual Basic Professional Edition for Windows, version 6.0 
- Microsoft Visual Basic Enterprise Edition for Windows, version 6.0 
- Microsoft Visual Basic Professional Edition for Windows, version 5.0 
- Microsoft Visual Basic Enterprise Edition for Windows, version 5.0 
- Microsoft Visual Basic Professional Edition, 16-bit, for Windows, version 4.0 
- Microsoft Visual Basic Professional Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 16-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows, version 4.0 
-------------------------------------------------------------------------------

SUMMARY
=======

Certain Visual Basic Data Access Objects (DAO), such as the Field, Recordset,
and TableDef objects, each have a Properties collection that uniquely
characterizes an instance of the object. You can use the default (built-in)
properties in the collection or you can create user-defined properties by using
the CreateProperty method.

The default properties available in the collection vary depending on the database
type. A set of extended properties, referred to as application- defined
properties, are available with Microsoft Access databases.

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

The built-in properties are available in the Properties collection for all
databases including Microsoft Access, Btrieve, dBASE, Microsoft FoxPro, Paradox,
and ODBC client-server databases such as SQL Server. For example, the following
built-in properties are available in the Properties collection of the TableDef
object (using DAO version 3.0):

   Name            SourceTableName
   Updatable       RecordCount
   DateCreated     ValidationRule
   LastUpdated     ValidationText
   Connect         ConflictTable
   Attributes

Additional application-defined properties are available for Microsoft Access
databases. For a complete list of built-in and application-defined properties,
please see the following topics in the Microsoft Access Help menu:

  Field Object, Fields Collection - Summary
  RecordSet Object, Recordsets Collection - Summary
  TableDef Object, TableDefs Collection - Summary

The application-defined properties will not be a part of the DAO's Properties
collection until the values are changed from their default values. You can
change an application-defined property default value by using Visual Basic code
or by using the Microsoft Access design environment. In Visual Basic code, use
the CreateProperty method just as you would to create user-defined properties.

Steps to Display the Properties Collection
------------------------------------------

1. Start a new project in Visual Basic. Form1 is created by default.

2. If using Visual Basic 5.0, establish a reference to DAO 3.5 by clicking
  References from the Project menu.

3. Add the following code to the Form1_Click procedure:

        Dim MyDB As Database
        Dim MySet As Recordset
        Dim MyProperty As Property
        Dim MyTableDef as TableDef

        ' Access database
        Set MyDB = DBEngine.Workspaces(0).OpenDatabase("biblio.mdb")
        Set MySet = MyDB.OpenRecordset("Authors", dbOpenTable)
        Set MyTableDef = MyDB("Authors")

        'display properties collection for Field
        For Each MyProperty In MySet(0).Properties
           List1.AddItem MyProperty.Name
        Next

        'display properties collection for Recordset
        For Each MyProperty In Myset.Properties
           List2.AddItem MyProperty.Name
        Next

        'display properties collection for Tabledef
        For Each MyProperty In MyTableDef.Properties
           List3.AddItem MyProperty.Name
        Next

        'Append an application-defined TableDef property by
        'changing its default value so it appears in the list
        On Error GoTo myerr:     'if RowHeight property exists trap error
        Set MyProperty = MyTableDef.CreateProperty("RowHeight")
        MyProperty.Type = dbinteger
        MyProperty.Value = 9
        MyTableDef.Properties.Append MyProperty

        myerr:
        MsgBox("RowHeight Property already exists, Please create another")

        'Print list again to see that RowHeight is displayed
        For Each MyProperty In MyTableDef.Properties
           List4.AddItem MyProperty.Name
        Next
        MySet.Close
        MyDb.Close
        On Error GoTo 0

4. Add four list boxes (List1, List2, List3, and List4) to Form1.

5. Run the program.

Additional query words: kbVBp400 kbVBp500 kbVBp600 kbdse kbDSupport kbVBp

======================================================================
Keywords          : kbGrpDSVBDB 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVB600Search kbVBA500 kbVBA600 kbVB500 kbVB600 kbVB400Search kbVB400 kbVB16bitSearch
Issue type        : kbinfo

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

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 1986-2002.