ACC: How to Return an UNC Path from an Existing Drive Letter

• Microsoft Access versions 7.0, 97

SUMMARY

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

This article demonstrates how to return the Universal Naming Convention (UNC) path for a mapped drive letter.

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 your version of the "Building Applications with Microsoft Access" manual.

MORE INFORMATION

To find the UNC path associated with a mapped network drive letter, follow these steps:

1. Create a module and type the following lines in the Declarations section:

         Option Explicit
   

         ' These represent the possible returns errors from API.
         Public Const ERROR_BAD_DEVICE = 1200&
         Public Const ERROR_CONNECTION_UNAVAIL = 1201&
         Public Const ERROR_EXTENDED_ERROR = 1208&
         Public Const ERROR_MORE_DATA = 234
         Public Const ERROR_NOT_SUPPORTED = 50&
         Public Const ERROR_NO_NET_OR_BAD_PATH = 1203&
         Public Const ERROR_NO_NETWORK = 1222&
         Public Const ERROR_NOT_CONNECTED = 2250&
         Public Const NO_ERROR = 0
   

         ' This API declaration is used to return the
         ' UNC path from a drive letter.
         Declare Function WNetGetConnection Lib "mpr.dll" Alias _
                          "WNetGetConnectionA" _
                          (ByVal lpszLocalName As String, _
                          ByVal lpszRemoteName As String, _
                          cbRemoteName As Long) As Long
   
   

2. Type the following procedure:

         Function GetUNCPath(strDriveLetter As String) As String
            On Local Error GoTo GetUNCPath_Err
            Dim Msg As String, lngReturn As Long
            Dim lpszLocalName As String
            Dim lpszRemoteName As String
            Dim cbRemoteName As Long
            lpszLocalName = strDriveLetter
            lpszRemoteName = String$(255, Chr$(32))
            cbRemoteName = Len(lpszRemoteName)
            lngReturn = WNetGetConnection(lpszLocalName, _
                                          lpszRemoteName, _
                                          cbRemoteName)
            Select Case lngReturn
               Case ERROR_BAD_DEVICE
                  Msg = "Error: Bad Device"
               Case ERROR_CONNECTION_UNAVAIL
                  Msg = "Error: Connection Un-Available"
               Case ERROR_EXTENDED_ERROR
                  Msg = "Error: Extended Error"
               Case ERROR_MORE_DATA
                  Msg = "Error: More Data"
               Case ERROR_NOT_SUPPORTED
                  Msg = "Error: Feature not Supported"
               Case ERROR_NO_NET_OR_BAD_PATH
                  Msg = "Error: No Network Available or Bad Path"
               Case ERROR_NO_NETWORK
                  Msg = "Error: No Network Available"
               Case ERROR_NOT_CONNECTED
                  Msg = "Error: Not Connected"
               Case NO_ERROR
                  ' all is successful...
            End Select
            If Len(Msg) Then
               MsgBox Msg, vbInformation
            Else
               ' Display the path in a Message box or return
               ' the UNC through the function.
               MsgBox Left$(lpszRemoteName, cbRemoteName)
               GetUNCPath = Left$(lpszRemoteName, cbRemoteName)
            End If
         GetUNCPath_End:
            Exit Function
         GetUNCPath_Err:
            MsgBox Err.Description, vbInformation
            Resume GetUNCPath_End
         End Function
   
   

3. To test this function, type the following line in the Debug window, and then press ENTER. A simple message box appears containing the UNC path of the specified network drive letter.

         ?GetUNCPath("h:")
   

   NOTE: This example assumes that you have a mapped network drive assigned to driver letter H.

   Some of the possible return values for the GetUNCPath function include ERROR_BAD_DEVICE, ERROR_CONNECTION_UNAVAIL, and ERROR_NOT_CONNECTED.

   Other run-time errors could be returned from the function and error trapping should be implemented.

REFERENCES

For more information about Declaring API Functions, search the Help Index for "Declare Statement," or ask the Microsoft Access 97 Office Assistant.