説明：レジストリを利用してアプリケーションの中で必要なDBドライバー、DSN名、データベース名などのDBへのアクセス情報を
　　　提供したり、ファイルパスやキーワードなど様々なアプリケーションの実行環境の変更によって変わり得る情報を
　　　提供することで、アプリケーションの修正なしに様々な環境に適応可能となります。

　STEP1：レジストリの決めたルートの配下に必要なキーを作成し、設計した文字列に値を設定する
　　　　［方法］　Windowの[スタート]の[ファイル名を指定して実行]を開いて　regedit　を実行する

STEP2：　レジストリエディタで上記図のようにHKEY_LOCAL_MACHINE→Mytest→SQLServer→｛DSN、Server、Database、
　　　　　　 UserID、PWD、Provider｝作成する

STEP3：　下記のようにCOMのソースを用意する(VBの場合)

STEP4：　アプリケーションからSTEP3で提供しているメソッド（Function)を呼んでレジストリから必要な情報を取得する

下記のソースは実戦でテストを受けたものです。

Option Explicit
Const TestConnection As String = "driver={SQL Server};SERVER=JPSQLDBDEV7;Database=[データベース名];UID=[ユーザー名];PWD=[パスワード];"
Const sRootKey = HKEY_LOCAL_MACHINE　　'ここはルートのキーワード(名)です
Const sSQLServerKey = "Software\OnlineStore\SQLServer"　　'ここは情報が格納されているレジストリの中のPathです
Const sFilePathKey = "Software\OnlineStore\FilePath"　　'ここは情報が格納されているレジストリの中のPathです

Public Function GetSQLServerConnectionString() As String

Dim sProvider As String
Dim sDSN As String
Dim sServerName As String
Dim sDBName As String
Dim sUserID As String
Dim sPassword As String

sProvider = QueryKeyValue(sRootKey, sSQLServerKey, "Provider")　　'レジストリからProvaiderを取得。例えば、SQLOLEDB.1
sDSN = QueryKeyValue(sRootKey, sSQLServerKey, "DSN")
sServerName = QueryKeyValue(sRootKey, sSQLServerKey, "Server")
sDBName = QueryKeyValue(sRootKey, sSQLServerKey, "Database")
sUserID = QueryKeyValue(sRootKey, sSQLServerKey, "UserID")
sPassword = QueryKeyValue(sRootKey, sSQLServerKey, "PWD")

GetSQLServerConnectionString = "PROVIDER=" & sProvider & ";DSN=" & sDSN & ";SERVER=" & sServerName & ";Database=" & sDBName & ";UID=" & sUserID & ";PWD=" & sPassword & ";"

End Function

Public Function GetFilePathString() As String

Dim sFilePath As String
sConfigFilePath = QueryKeyValue(sRootKey, sFileKey, "Filepath")
GetFilePathString =　sFilePathKey

End Function

'This module contains all common API calls and functions
'shared among all COM objects such as registry access, etc.

Option Explicit

'/* Win32 constant and functions related to manager NT Task bar
Public Declare Function Shell_NotifyIcon Lib "shell32.dll" Alias _
"Shell_NotifyIconA" (ByVal dwMessage As Long, lpData As NOTIFYICONDATA) As Long
Public Type NOTIFYICONDATA
cbSize As Long
hwnd As Long
uID As Long
uFlags As Long
uCallbackMessage As Long
hIcon As Long
szTip As String * 64
End Type

'/* Win32 constant and functions related to registry
Public Const HKEY_LOCAL_MACHINE = &H80000002
Public Const HKEY_CLASSES_ROOT = &H80000000
Public Const HKEY_CURRENT_CONFIG = &H80000005
Public Const HKEY_CURRENT_USER = &H80000001
Public Const HKEY_DYN_DATA = &H80000006

Public Const REG_SZ = 1 ' Unicode null terminated string
Public Const REG_MULTI_SZ = 7 ' Multiple Unicode strings
Public Const REG_DWORD As Long = 4

Public Const READ_CONTROL = &H20000
Public Const STANDARD_RIGHTS_READ = (READ_CONTROL)
Public Const SYNCHRONIZE = &H100000

Public Const KEY_CREATE_LINK = &H20
Public Const KEY_CREATE_SUB_KEY = &H4
Public Const KEY_ENUMERATE_SUB_KEYS = &H8
Public Const KEY_EVENT = &H1 ' Event contains key event record

Public Const KEY_NOTIFY = &H10
Public Const KEY_SET_VALUE = &H2
Public Const KEY_QUERY_VALUE = &H1
Public Const KEY_ALL_ACCESS = &H3F

Public Const NIM_ADD = &H0
Public Const NIM_MODIFY = &H1
Public Const NIM_DELETE = &H2
Public Const NIF_MESSAGE = &H1
Public Const NIF_ICON = &H2
Public Const NIF_TIP = &H4 'Make your own constant, e.g.:
Public Const NIF_DOALL = NIF_MESSAGE Or NIF_ICON Or NIF_TIP
Public Const WM_MOUSEMOVE = &H200
Public Const WM_LBUTTONDBLCLK = &H203
Public Const WM_LBUTTONDOWN = &H201
Public Const WM_RBUTTONDOWN = &H204

'EA PROCESSOR status constant
Public Const EAFP_ST_IDLE = 1 'no polling, no working
Public Const EAFP_ST_PULLING = 2 'in polling mode
Public Const EAFP_ST_WORKING = 3 'in working mode

'EA file status constant
Public Const EAFP_FST_READY = 1
Public Const EAFP_FST_INPROC = 2
Public Const EAFP_FST_PROCESSED = 3
Public Const EAFP_FST_REJECTED = 4

'EA Processor error notification method
Public Const EAFP_NM_EMAIL = 1
Public Const EAFP_NM_TODB = 2
Public Const EAFP_NM_TOFILE = 3
Public Const EAFP_NM_WINMSG = 4

Public Const KEY_READ = ((STANDARD_RIGHTS_READ Or KEY_QUERY_VALUE Or KEY_ENUMERATE_SUB_KEYS Or KEY_NOTIFY) And (Not SYNCHRONIZE))

Public Declare Function RegOpenKey Lib "advapi32.dll" Alias "RegOpenKeyA" (ByVal hKey As Long, ByVal lpSubKey As String, phkResult As Long) As Long
Public 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
Public Declare Function RegQueryValue Lib "advapi32.dll" Alias "RegQueryValueA" (ByVal hKey As Long, ByVal lpSubKey As String, ByVal lpValue As String, lpcbValue As Long) As Long
Public Declare Function RegQueryValueEx Lib "advapi32.dll" Alias "RegQueryValueExA" (ByVal hKey As Long, ByVal lpValueName As String, ByVal lpReserved As Long, lpType As Long, ByVal lpData As String, lpcbData As Long) As Long
Public Declare Function RegCloseKey Lib "advapi32.dll" (ByVal hKey As Long) As Long
Public Declare Function RegSetValue Lib "advapi32.dll" Alias "RegSetValueA" (ByVal hKey As Long, ByVal lpSubKey As String, ByVal dwType As Long, ByVal lpData As String, ByVal cbData As Long) As Long
Public Declare Function RegSetValueEx Lib "advapi32.dll" Alias "RegSetValueExA" (ByVal hKey As Long, ByVal lpValueName As String, ByVal Reserved As Long, ByVal dwType As Long, lpData As Any, ByVal cbData As Long) As Long ' Note that if you declare the lpData parameter as String, you must pass it By Value.

Declare Function RegQueryValueExString Lib "advapi32.dll" Alias "RegQueryValueExA" (ByVal hKey As Long, ByVal lpValueName As String, ByVal lpReserved As Long, lpType As Long, ByVal lpData As String, lpcbData As Long) As Long
Declare Function RegQueryValueExLong Lib "advapi32.dll" Alias "RegQueryValueExA" (ByVal hKey As Long, ByVal lpValueName As String, ByVal lpReserved As Long, lpType As Long, lpData As Long, lpcbData As Long) As Long
Declare Function RegQueryValueExNULL Lib "advapi32.dll" Alias "RegQueryValueExA" (ByVal hKey As Long, ByVal lpValueName As String, ByVal lpReserved As Long, lpType As Long, ByVal lpData As Long, lpcbData As Long) As Long
Declare Function RegSetValueExString Lib "advapi32.dll" Alias "RegSetValueExA" (ByVal hKey As Long, ByVal lpValueName As String, ByVal Reserved As Long, ByVal dwType As Long, ByVal lpValue As String, ByVal cbData As Long) As Long
Declare Function RegSetValueExLong Lib "advapi32.dll" Alias "RegSetValueExA" (ByVal hKey As Long, ByVal lpValueName As String, ByVal Reserved As Long, ByVal dwType As Long, lpValue As Long, ByVal cbData As Long) As Long

Public Function SetValueEx(ByVal hKey As Long, sValueName As String, lType As Long, vValue As Variant) As Long

Dim lValue As Long
Dim sValue As String

Select Case lType

Case REG_SZ
sValue = vValue & Chr$(0)
SetValueEx = RegSetValueExString(hKey, sValueName, 0&, lType, sValue, Len(sValue))

Case REG_DWORD
lValue = vValue
SetValueEx = RegSetValueExLong(hKey, sValueName, 0&, lType, lValue, 4)

End Select

End Function

Public Function QueryKeyValue(RootKey As Long, sKeyName As String, sValueName As String) As Variant

Dim lRetVal As Long 'result of the API functions
Dim hKey As Long 'handle of opened key

lRetVal = RegOpenKeyEx(RootKey, sKeyName, 0, KEY_ALL_ACCESS, hKey)
lRetVal = QueryValueEx(hKey, sValueName, QueryKeyValue)
RegCloseKey (hKey)

End Function

Public Sub SetKeyValue(RookKey As Long, sKeyName As String, sValueName As String, vValueSetting As Variant, lValueType As Long)

Dim lRetVal As Long 'result of the SetValueEx function
Dim hKey As Long 'handle of open key

'open the specified key
lRetVal = RegOpenKeyEx(RookKey, sKeyName, 0, KEY_ALL_ACCESS, hKey)
lRetVal = SetValueEx(hKey, sValueName, lValueType, vValueSetting)
RegCloseKey (hKey)

End Sub

Public Function QueryValueEx(ByVal lhKey As Long, ByVal szValueName As String, vValue As Variant) As Long

Dim cch As Long
Dim lrc As Long
Dim lType As Long
Dim lValue As Long
Dim sValue As String

On Error GoTo QueryValueExError

' Determine the size and type of data to be read
lrc = RegQueryValueExNULL(lhKey, szValueName, 0&, lType, 0&, cch)
If lrc <> ERROR_NONE Then Error 5

Select Case lType
' For strings
Case REG_SZ:
sValue = String(cch, 0)
lrc = RegQueryValueExString(lhKey, szValueName, 0&, lType, sValue, cch)
If lrc = ERROR_NONE Then
vValue = Left$(sValue, cch - 1)
Else
vValue = Empty
End If
' For DWORDS
Case REG_DWORD:
lrc = RegQueryValueExLong(lhKey, szValueName, 0&, lType, lValue, cch)
If lrc = ERROR_NONE Then vValue = lValue
Case Else
'all other data types not supported
lrc = -1
End Select

QueryValueExExit:
QueryValueEx = lrc
Exit Function
QueryValueExError:
Resume QueryValueExExit

End Function