The information in this article applies to:
- Microsoft Access versions 2.0, 7.0
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:
- 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
- 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.
Keywords : kbprg PgmHowTo MdlDao
Version : 2.0 7.0
Platform : WINDOWS
Hardware : x86
Issue type : kbhowto