Access开发培训
网站公告
·Access专家课堂QQ群号:151711184    ·Access快速开发平台下载地址及教程    ·欢迎加入Access专家课堂微信群!    ·如何快速搜索本站文章|示例|资料    
您的位置: 首页 > 技术文章 > Access数据库-模块/函数/VBA

access下如何恢复已经删除的记录;如何恢复已经删除的表、窗体等等对象

时 间:2015-02-04 08:29:27
作 者:宏鹏(转载)   ID:21115  城市:上海
摘 要:access下如何恢复已经删除的记录
正 文:

问题:

 如何恢复已经删除的记录;如何恢复已经删除的表、窗体等等对象

1、我用 Delete FROM TABLE 删除了一些记录,现在发现误删除了,该如何恢复? 
2、我直接手动删除或者用 Drop TABLE 删除了一个表,现在发现是误删除了,该如何恢复?
3、我手动删除了一个窗体,该如何恢复? 
4、我删除了记录,可是数据库体积并没有减小,那么是否能找回记录呢? 

 
回答:  
1、已经删除的记录是无法恢复的,ACCESS 不是 FOXPRO,MDB 格式不是 DBF 格式,没有逻辑删除和物理删除的概念,一旦删除就无法恢复了。 
2、无法恢复,但是你可以查看一下,有没有隐藏的以 "~" 符号开头的表,更改该表的名称有可能找回你需要的表。 
3、无法恢复,但是你可以查看一下有没有系统隐藏的对象,有时候对象被删除时系统并不直接删除,而是更改对象名后隐藏它。 
4、数据库体积的确没有变小,你压缩修复数据库后体积就会变小了。那是因为在二进制上你的数据的确没有被删除,仍然存放在磁盘的某个扇区,但是微软没有提供 MDB 格式二进制组织方式的参考资料(微软也不会提供,其他第三方公司也没有权利直接反编译 MDB 格式)。至今为止,中国大陆我也没有看到过相关的参考资料。所以目前为止,你已经删除的数据是无法恢复的。但是你可以尝试使用磁盘恢复软件来找到恢复数据的方法,但是该方法不在本文讨论范围。 
 
建议:在建立数据库结构时,可以在各个表中再多加一个 ISDEL 字段,删除记录时不使用 Delete FROM ,而使用 Update TABLE SET ISDEL=TRUE 这样的语句,然后在界面上不显示 ISDEL=TRUE 的记录即可。 
  

 如果还没有被压缩理论上可以。试试这段代码吧。加在access模块中 
 恢复删除的工作表(未被压缩)
 Public Function FnUndeleteObjects() As Boolean 
  On Error GoTo ErrorHandler: 
  Dim strObjectName           As String 
  Dim rsTables                As DAO.Recordset 
  Dim dbsDatabase             As DAO.Database 
  Dim tDef                    As DAO.TableDef 
  Dim qDef                    As DAO.QueryDef 
  Dim intNumDeletedItemsFound As Integer 
  Set dbsDatabase = CurrentDb 
  For Each tDef In dbsDatabase.TableDefs 
      'This is actually used as a 'Deleted Flag' 
      If tDef.Attributes And dbHiddenObject Then 
         strObjectName = FnGetDeletedTableNameByProp(tDef.Name) 
         strObjectName = InputBox("A deleted TABLE has been found." & _ 
                         vbCrLf & vbCrLf & _ 
                         "To undelete this object, enter a new name:", _ 
                         "Access Undelete Table", strObjectName) 

         If Len(strObjectName) > 0 Then 
            FnUndeleteTable CurrentDb, tDef.Name, strObjectName 
         End If 
         intNumDeletedItemsFound = intNumDeletedItemsFound + 1 
      End If 
  Next tDef 

  For Each qDef In dbsDatabase.QueryDefs 
      'Note 'Attributes' flag is not exposed for QueryDef objects, 
      'We could look up the flag by using MSysObjects but 
      'new queries don't get written to MSysObjects until 
      'Access is closed. Therefore we'll just check the 
      'start of the name is '~TMPCLP' ... 
      If InStr(1, qDef.Name, "~TMPCLP") = 1 Then 
         strObjectName = "" 
         strObjectName = InputBox("A deleted QUERY has been found." & _ 
                         vbCrLf & vbCrLf & _ 
                         "To undelete this object, enter a new name:", _ 
                         "Access Undelete Query", strObjectName) 

         If Len(strObjectName) > 0 Then 
            If FnUndeleteQuery(CurrentDb, qDef.Name, strObjectName) Then 
               'We'll rename the deleted object since we've made a 
               'copy and won't be needing to re-undelete it. 
               '(To break the condition "~TMPCLP" in future...) 
                qDef.Name = "~TMPCLQ" & Right$(qDef.Name, Len(qDef.Name) - 7) 
             End If 
         End If 
         intNumDeletedItemsFound = intNumDeletedItemsFound + 1 
      End If 
  Next qDef 
  If intNumDeletedItemsFound = 0 Then 
     MsgBox "Unable to find any deleted tables/queries to undelete!" 
  End If 

  Set dbsDatabase = Nothing 
  FnUndeleteObjects = True 
ExitFunction: 
  Exit Function 
ErrorHandler: 
  MsgBox "Error occured in FnUndeleteObjects() - " & _ 
         Err.Description & " (" & CStr(Err.Number) & ")" 
  GoTo ExitFunction 
End Function 


Private Function FnUndeleteTable(dbDatabase As DAO.Database, _ 
                 strDeletedTableName As String, _ 
                 strNewTableName As String) 

  'Module (c) 2005 Wayne Phillips (http://www.everythingaccess.com) 
  'Written 18/04/2005 
  Dim tDef As DAO.TableDef 
  Set tDef = dbDatabase.TableDefs(strDeletedTableName) 
  'Remove the Deleted Flag... 
  tDef.Attributes = tDef.Attributes And Not dbHiddenObject 
  'Rename the deleted object to the original or new name... 
  tDef.Name = strNewTableName 
  dbDatabase.TableDefs.Refresh 
  Application.RefreshDatabaseWindow 
  Set tDef = Nothing 
End Function 

Private Function FnUndeleteQuery(dbDatabase As DAO.Database, _ 
                 strDeletedQueryName As String, _ 
                 strNewQueryName As String) 

  'Module (c) 2005 Wayne Phillips (http://www.everythingaccess.com) 
  'Written 18/04/2005 
  'We can't just remove the Deleted flag on queries 
  '('Attributes' is not an exposed property) 
  'So instead we create a new query with the SQL... 

  'Note: Can't use DoCmd.CopyObject as it copies the dbHiddenObject attribute! 

  If FnCopyQuery(dbDatabase, strDeletedQueryName, strNewQueryName) Then 
     FnUndeleteQuery = True 
     Application.RefreshDatabaseWindow 
  End If 
End Function 


Private Function FnCopyQuery(dbDatabase As DAO.Database, _ 
                 strSourceName As String, _ 
                 strDestinationName As String) 

  'Module (c) 2005 Wayne Phillips (http://www.everythingaccess.com) 
  'Written 18/04/2005 
  On Error GoTo ErrorHandler: 

  Dim qDefOld As DAO.QueryDef 
  Dim qDefNew As DAO.QueryDef 
  Dim Field As DAO.Field 

  Set qDefOld = dbDatabase.QueryDefs(strSourceName) 
  Set qDefNew = dbDatabase.CreateQueryDef(strDestinationName, qDefOld.SQL) 

  'Copy root query properties... 
  FnCopyLvProperties qDefNew, qDefOld.Properties, qDefNew.Properties 

  For Each Field In qDefOld.Fields 
      'Copy each fields individual properties... 
      FnCopyLvProperties qDefNew.Fields(Field.Name), _ 
                         Field.Properties, _ 
                         qDefNew.Fields(Field.Name).Properties 
  Next Field 
  dbDatabase.QueryDefs.Refresh 
  FnCopyQuery = True 
ExitFunction: 
  Set qDefNew = Nothing 
  Set qDefOld = Nothing 
  Exit Function 
ErrorHandler: 
  MsgBox "Error re-creating query '" & strDestinationName & "':" & vbCrLf & _ 
         Err.Description & " (" & CStr(Err.Number) & ")" 
  GoTo ExitFunction 
End Function 

Private Function PropExists(Props As DAO.Properties, strPropName As String) As Boolean 
  'Module (c) 2005 Wayne Phillips (http://www.everythingaccess.com) 
  'Written 18/04/2005 
  'If properties fail to be created, we'll just ignore the errors 
  On Error Resume Next 
  Dim Prop As DAO.Property 
  For Each Prop In Props 
      If Prop.Name = strPropName Then 
         PropExists = True 
         Exit Function ' Short circuit 
      End If 
  Next Prop 
  PropExists = False 
End Function 

Private Sub FnCopyLvProperties(objObject As Object, OldProps As DAO.Properties, NewProps As DAO.Properties) 
  'Module (c) 2005 Wayne Phillips (http://www.everythingaccess.com) 
  'Written 18/04/2005 
  'If properties fail to be created, we'll just ignore the errors 
  On Error Resume Next 
  Dim Prop As DAO.Property 
  Dim NewProp As DAO.Property 
  For Each Prop In OldProps 
      If Not PropExists(NewProps, Prop.Name) Then 
         If IsNumeric(Prop.Value) Then 
            NewProps.Append objObject.CreateProperty(Prop.Name, Prop.Type, CLng(Prop.Value)) 
         Else 
            NewProps.Append objObject.CreateProperty(Prop.Name, Prop.Type, Prop.Value) 
         End If 
      Else 
         With NewProps(Prop.Name) 
              .Type = Prop.Type 
              .Value = Prop.Value 
         End With 
      End If 
  Next Prop 
End Sub 

Private Function FnGetDeletedTableNameByProp(strRealTableName As String) As String 
  'Module (c) 2005 Wayne Phillips (http://www.everythingaccess.com) 
  'Written 18/04/2005 
  'If an error occurs here, just ignore (user will override the blank name) 
  On Error Resume Next 
  Dim i As Long 
  Dim strNameMap As String 

  'Look up the Unicode translation NameMap property to try to guess the 
  'original table name... (Access 2000+ only - and doesn't always exist?!) 

  strNameMap = CurrentDb.TableDefs(strRealTableName).Properties("NameMap") 
  strNameMap = Mid(strNameMap, 23) 'Offset of the table name... 

  'Find the null terminator... 
  i = 1 
  If Len(strNameMap) > 0 Then 
     While (i < Len(strNameMap)) And (Asc(Mid(strNameMap, i)) <> 0) 
       i = i + 1 
     Wend 
  End If 
  FnGetDeletedTableNameByProp = Left(strNameMap, i - 1) 
End Function


Access软件网官方交流QQ群 (群号:483923997)       Access源码网店

常见问答:

技术分类:

相关资源:

专栏作家

关于我们 | 服务条款 | 在线投稿 | 友情链接 | 网站统计 | 网站帮助