Question

I have an Excel application in which I want to present the user with a list of the Data Source Names (ie: DSN’s), whereby s/he can choose what data source to use.

Hopefully once I’ve got the list, I can easily access the DSN properties to connect to the appropriate database.

Please note, I do not want to use a DSN-less connection.

Answer 1

The DSN entries are stored in the registry in the following keys.

HKEY_CURRENT_USER\Software\ODBC\ODBC.INI\ODBC Data Sources HKEY_LOCAL_MACHINE\SOFTWARE\ODBC\ODBC.INI\ODBC Data Sources

This contains the list of all defined DSN. This acts as an global index and the specific details for each DSN are stored in a key with the DSN name under:

HKEY_CURRENT_USER\Software\ODBC\ODBC.INI HKEY_LOCAL_MACHINE\SOFTWARE\ODBC\ODBC.INI

Create some entries in both User DSN and System DSN tabs from Data Sources (ODBC) control panel applet and check how these values are stored in the registry.

The following example enumerate the DSN defined for the user trough Control Panel > Administrative Tools > Data Sources (ODBC) [User Dsn Tab].

http://support.microsoft.com/kb/178755

  Option Explicit    Private Declare Function RegOpenKeyEx Lib 'advapi32.dll' _       Alias 'RegOpenKeyExA' _       (ByVal hKey As Long, _       ByVal lpSubKey As String, _       ByVal ulOptions As Long, _       ByVal samDesired As Long, phkResult As Long) As Long    Private Declare Function RegEnumValue Lib 'advapi32.dll' _       Alias 'RegEnumValueA' _       (ByVal hKey As Long, _       ByVal dwIndex As Long, _       ByVal lpValueName As String, _       lpcbValueName As Long, _       ByVal lpReserved As Long, _       lpType As Long, _       lpData As Any, _       lpcbData As Long) As Long    Private Declare Function RegCloseKey Lib 'advapi32.dll' _       (ByVal hKey As Long) As Long    Const HKEY_CLASSES_ROOT = &H80000000   Const HKEY_CURRENT_USER = &H80000001   Const HKEY_LOCAL_MACHINE = &H80000002   Const HKEY_USERS = &H80000003    Const ERROR_SUCCESS = 0&    Const SYNCHRONIZE = &H100000   Const STANDARD_RIGHTS_READ = &H20000   Const STANDARD_RIGHTS_WRITE = &H20000   Const STANDARD_RIGHTS_EXECUTE = &H20000   Const STANDARD_RIGHTS_REQUIRED = &HF0000   Const STANDARD_RIGHTS_ALL = &H1F0000   Const KEY_QUERY_VALUE = &H1   Const KEY_SET_VALUE = &H2   Const KEY_CREATE_SUB_KEY = &H4   Const KEY_ENUMERATE_SUB_KEYS = &H8   Const KEY_NOTIFY = &H10   Const KEY_CREATE_LINK = &H20   Const KEY_READ = ((STANDARD_RIGHTS_READ Or _                     KEY_QUERY_VALUE Or _                     KEY_ENUMERATE_SUB_KEYS Or _                     KEY_NOTIFY) And _                     (Not SYNCHRONIZE))    Const REG_DWORD = 4   Const REG_BINARY = 3   Const REG_SZ = 1    Private Sub Command1_Click()      Dim lngKeyHandle As Long      Dim lngResult As Long      Dim lngCurIdx As Long      Dim strValue As String      Dim lngValueLen As Long      Dim lngData As Long      Dim lngDataLen As Long      Dim strResult As String       lngResult = RegOpenKeyEx(HKEY_CURRENT_USER, _              'SOFTWARE\ODBC\ODBC.INI\ODBC Data Sources', _               0&, _               KEY_READ, _               lngKeyHandle)       If lngResult <> ERROR_SUCCESS Then          MsgBox 'Cannot open key'          Exit Sub      End If       lngCurIdx = 0      Do         lngValueLen = 2000         strValue = String(lngValueLen, 0)         lngDataLen = 2000          lngResult = RegEnumValue(lngKeyHandle, _                                  lngCurIdx, _                                  ByVal strValue, _                                  lngValueLen, _                                  0&, _                                  REG_DWORD, _                                  ByVal lngData, _                                  lngDataLen)         lngCurIdx = lngCurIdx + 1          If lngResult = ERROR_SUCCESS Then            strResult = strResult & lngCurIdx & ': ' & Left(strValue, lngValueLen) & vbCrLf         End If      Loop While lngResult = ERROR_SUCCESS      Call RegCloseKey(lngKeyHandle)       Call MsgBox(strResult, vbInformation)   End Sub