はい、それは完全に可能です。2つのDBの比較と変更のログ記録に関する注意事項を次に示します。
この手順では、モジュールの上部に次のものが必要です。
Dim strFileNew As String
Dim strFileOld As String
Dim strLog As String
Dim dbOld As Database
変数には次のものが含まれる場合があります。
strLog = "log.txt"
strFileNew = "z:\docs\dbNew.mdb"
strFileOld = "z:\docs\dbOld.mdb"
Set dbOld = OpenDatabase(strFileOld)
次に、比較:
Sub LogCompareDB(db As Database)
''References : Windows Script Host Object Model
'' This is set by default for a number of versions
'' : Microsoft DAO x.x Object Library
'' For 2010, the DAO library is called
'' :Microsoft Office 12.0 Access Database Engine Object Library
Dim tdf As TableDef
Dim rs0 As DAO.Recordset
Dim rs1 As DAO.Recordset
Dim fld As DAO.Field
Dim idx As Index
Dim idxPrimary As Index
Dim strIndexList As String
Dim strIndex As String
Dim strID As String
Dim strSQL As String
Dim strChanged As String
Dim blnNew As Boolean
Dim fs As New FileSystemObject
Dim ts As TextStream
Set ts = fs.CreateTextFile(strLog, True)
''For each table in the old database
''(It would probably be a good idea to check the
''new database for added tables)
For Each tdf In db.TableDefs
'' Skip system tables
If Left(tdf.Name, 4) <> "MSys" Then
strIndex = vbNullString
Set idxPrimary = Nothing
strIndexList = vbNullString
''Get the primary index and index fields
For Each idx In tdf.Indexes
If idx.Primary = True Then
Set idxPrimary = idx
For Each fld In idx.Fields
strIndex = strIndex & " AND t0.[" & fld.Name _
& "] = t1.[" & fld.Name & "]"
strIndexList = strIndexList & "," & fld.Name
Next
strIndex = Mid(strIndex, 5)
End If
Next
''There is no basis for comparison if there is no index.
''A unique index would also be a possibility, but hey, let's
''not go over the top :)
If strIndex > vbNullString Then
''Select all records from the table for both databases
strSQL = "SELECT * FROM [;DATABASE=" & strFileNew & "].[" _
& tdf.Name & "] As t0 LEFT JOIN [" _
& tdf.Name & "] As t1 ON " & strIndex
Set rs0 = db.OpenRecordset(strSQL)
''A convenient list of fields from the old database
''It would probably be a good idea to check the
''new database for added fields.
strSQL = "SELECT * FROM [;DATABASE=" & strFileOld & "].[" _
& tdf.Name & "] As t0 WHERE 1=2"
Set rs1 = db.OpenRecordset(strSQL)
Do While Not rs0.EOF
strID = vbNullString
blnNew = False
''If the index fields are null, then it is a new record
For Each fld In idxPrimary.Fields
strID = strID & fld.Name & ": " & rs0("[t0." & fld.Name & "]") & vbCrLf
If IsNull(rs0("[t1." & fld.Name & "]")) Then
blnNew = True
End If
Next
If blnNew Then
''Write to log
ts.WriteLine "NEW RECORD " & strID & vbCrLf
Else
''Not a new record, so is it a changed record?
strChanged = vbNullString
For Each fld In rs1.Fields
''No need to check index fields, because they are equal
If InStr(strIndexList, fld.Name) = 0 Then
''Add null string for purposes of comparison ''trailing
If "" & rs0("[t0." & fld.Name & "]") <> "" & rs0("[t1." & fld.Name & "]") Then
strChanged = strChanged & vbCrLf _
& fld.Name & " Is: " & Trim(rs0("[t0." & fld.Name & "]")) _
& " Was: " & Trim(rs0("[t1." & fld.Name & "]"))
End If
End If
Next
If strChanged <> vbNullString Then
''Write to log
ts.WriteLine "CHANGED RECORD " & strID
ts.WriteLine strChanged & vbCrLf
End If
End If
rs0.MoveNext
Loop
Else
ts.WriteLine "NO PRIMARY INDEX " & tdf.Name & vbCrLf
End If
End If
Next
ts.Close
FollowHyperlink strLog
End Sub