ACC: How to Create a Custom Database Version Using DAO (132025)


The information in this article applies to:

  • Microsoft Access 2.0
  • Microsoft Access for Windows 95 7.0
This article was previously published under Q132025

SUMMARY

Advanced: Requires expert coding, interoperability, and multiuser skills.

This article demonstrates four user-defined functions that you can use to control a custom database's version number, and then shows you how to use the functions to manage your databases' version numbers. These functions are useful when you need to know the specific version of your database application before you perform a task.

This article assumes that you are familiar with Visual Basic for Applications and with creating Microsoft Access applications using the programming tools provided with Microsoft Access. For more information about Visual Basic for Applications, please refer to the "Building Applications with Microsoft Access for Windows 95" manual.

NOTE: Visual Basic for Applications (used in Microsoft Access for Windows 95 version 7.0) is called Access Basic in version 2.0. For more information about Access Basic, please refer to the "Building Applications" manual.

MORE INFORMATION

The Properties collection in a Microsoft Access database applies to all objects in that database, such as forms, reports, tables, and so on. They are assigned by Microsoft Access and the developer through the user interface and when objects are created, modified, and saved. At the top level of the DAO (data access objects) model, the database contains properties that identify specific information concerning the version of the Microsoft Access database file format, the current Microsoft Access version, the database collating order, and so on.

The Properties collection supports the use of user-defined properties that can be appended to the Properties collection and used in functions.

To create the four functions that give you control over a custom database's version number, follow these steps:

  1. Create a new module and type the following four functions.

    NOTE: In the following sample code, an underscore (_) at the end of a line is used as a line-continuation character. Remove the underscore from the end of the line when re-creating this code in Access Basic. 
          ' **********************************************************
      ' Function: AddDBVersion()
      '  Purpose: Used to add a new Version property to the
      '           current database.
      '   Return: True(-1) for success, False(0) for failure.
      ' **********************************************************


      Function AddDBVersion (MyVersionNum As String) As Integer

         On Local Error GoTo AddDBVersion_Err

         Dim MyWS As WorkSpace
         Dim MyDB As Database
         Dim MyVersion As Property

         ' Set all DAO objects.
         Set MyWS = DBEngine.Workspaces(0)
         Set MyDB = MyWS.Databases(0)

         ' Assign and append the Version number.
         Set MyVersion = MyDB.CreateProperty("MyVersion", DB_TEXT, _
                         MyVersionNum)
         MyDB.Properties.Append MyVersion

         ' Pass back success.
         AddDBVersion = True

      AddDBVersion_End:
         Exit Function

      AddDBVersion_Err:
         MsgBox Error$
         Resume AddDBVersion_End

      End Function

      ' **********************************************************
      ' Function: UpdateDBVersion()
      '  Purpose: Used to edit the Version property in the
      '           current database.
      '   Return: True(-1) for success, False(0) for failure.
      ' **********************************************************

      Function UpdateDBVersion (MyVersionNum As String) As Integer

         On Local Error GoTo UpdateDBVersion_Err

         Dim MyWS As WorkSpace
         Dim MyDB As Database

         ' Set all DAO objects.
         Set MyWS = DBEngine.Workspaces(0)
         Set MyDB = MyWS.Databases(0)

         ' Edit the Version property.
         MyDB.Properties("MyVersion") = MyVersionNum

         ' Pass back success.
         UpdateDBVersion = True

      UpdateDBVersion_End:
         Exit Function

      UpdateDBVersion_Err:
         MsgBox Error$
         Resume UpdateDBVersion_End

      End Function

      ' ***********************************************************
      ' Function: GetDBVersion()
      '  Purpose: Used to return the Version property to the
      '           calling routine or expression.
      '   Return: Version for success, an empty string for failure.
      ' ***********************************************************

      Function GetDBVersion () As String

         On Local Error GoTo GetDBVersion_Err

         Dim MyWS As WorkSpace
         Dim MyDB As Database

         ' Set all DAO objects.
         Set MyWS = DBEngine.Workspaces(0)
         Set MyDB = MyWS.Databases(0)

         ' Return the version number.
         GetDBVersion = MyDB.Properties("MyVersion")

      GetDBVersion_End:
         Exit Function

      GetDBVersion_Err:
         MsgBox Error$
         Resume GetDBVersion_End

      End Function

      ' **********************************************************
      ' Function: DeleteDBVersion()
      '  Purpose: Used to remove the Version property from the
      '           current database.
      '   Return: True(-1) for success, False(0) for failure.
      ' **********************************************************

      Function DeleteDBVersion () As Integer

         On Local Error GoTo DeleteDBVersion_Err

         Dim MyWS As WorkSpace
         Dim MyDB As Database
         Dim MyVersion As Property

         ' Set all DAO objects.
         Set MyWS = DBEngine.Workspaces(0)
         Set MyDB = MyWS.Databases(0)

         ' Delete the Version property.
         MyDB.Properties.Delete "MyVersion"

         ' Pass back success.
         DeleteDBVersion = True

      DeleteDBVersion_End:
         Exit Function

      DeleteDBVersion_Err:
         MsgBox Error$
         Resume DeleteDBVersion_End

      End Function
  2. To use the functions, use the following code in an event procedure or your specific code.

    • To create a version number: 
               If AddDBVersion("1.00") Then
            MsgBox "Version Number Created"
         Else
            MsgBox "Unable to Change Version Number "
         End If
    • To edit a version number: 
               If UpdateDBVersion("2.00") Then
            MsgBox "Version Number Updated"
         Else
            MsgBox "Unable to Change Version Number "
         End If
    • To return a version number:

      MsgBox "Version Number is " & GetDBVersion()
    • To return a version number on a form or report:

      Create a Text Control and set the control's ControlSource property to =GetDBVersion()
    • To delete a version number: 
               If DeleteDBVersion() Then
            MsgBox "Version Number Deleted"
         Else
            MsgBox "Unable to Delete Version Number"
         End If

REFERENCES

Microsoft Access "Building Applications," version 2.0, Chapter 5, "Access Basic Fundamentals," pages 113-132

Microsoft Access "Building Applications," version 2.0, Chapter 7, "Objects and Collections," pages 174-181

For more information about the CreateProperty, search for "CreateProperty," and then "CreateProperty Method (Data Access)" using the Microsoft Access Help menu.
Modification Type:MinorLast Reviewed:10/11/2006
Keywords:kbhowto kbProgramming KB132025
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