推薦：如何用Access 輕松打造花店訂單系統(tǒng)
任務(wù)名稱:打造花店訂單系統(tǒng) 任務(wù)描述:小特的MM開了一家花店，生意特別火，招了三個小工還有點忙不過來。每天都有不少人通過電話或直接到花店訂購鮮花，大多數(shù)客戶還希望能在指定時間將所購鮮花送到指定地點。小特便用Access幫MM定制了一個花店訂單系統(tǒng):通過這

Private Const GENERIC_WRITE = &H40000000
Private Const OPEN_EXISTING = 3
Private Const FILE_SHARE_READ = &H1
Private Const FILE_SHARE_WRITE = &H2
Private Declare Function SetFileTimeWrite Lib "kernel32" Alias _
"SetFileTime" (ByVal hFile As Long, lpCreateTime As FILETIME, _
ByVal NullP As Long, ByVal NullP2 As Long) As Long
Private Declare Function SystemTimeToFileTime Lib "kernel32" _
(lpSystemTime As SYSTEMTIME, lpFileTime As FILETIME) As Long
Private Declare Function CreateFile Lib "kernel32" Alias "CreateFileA" _
(ByVal lpFileName As String, ByVal dwDesiredAccess As Long, ByVal _
dwShareMode As Long, ByVal lpSecurityAttributes As Long, ByVal _
dwCreationDisposition As Long, ByVal dwFlagsAndAttributes As Long, _
ByVal hTemplateFile As Long) As Long
Private Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Long) _
As Long
Private Declare Function LocalFileTimeToFileTime Lib "kernel32" _
(lpLocalFileTime As FILETIME, lpFileTime As FILETIME) As Long
Private Sub Command1_Click()
Dim Year As Integer, Month As Integer, Day As Integer
Dim Hour As Integer, Minute As Integer, Second As Integer
Dim TimeStamp As Variant, Filename As String, X As Integer
Year = 2001: Month = 3: Day = 13 ' 準備設(shè)定的“創(chuàng)建日期”
Hour = 12: Minute = 0: Second = 26
TimeStamp = DateSerial(Year, Month, Day) + TimeSerial(Hour, Minute, Second)
Filename = "D:\VB6_Test\MDB_Password\Pass_Protected_DB.mdb" ' 目標文件名
X = ModifyFileStamp(Filename, TimeStamp)
End Sub
Function ModifyFileStamp(Filename As String, TimeStamp As Variant) As Integer
Dim X As Long, Handle As Long, System_Time As SYSTEMTIME
Dim File_Time As FILETIME, Local_Time As FILETIME
System_Time.wYear = Year(TimeStamp): System_Time.wMonth = Month(TimeStamp)
System_Time.wDay = Day(TimeStamp)
System_Time.wDayOfWeek = Weekday(TimeStamp) - 1
System_Time.wHour = Hour(TimeStamp): System_Time.wSecond = Second(TimeStamp)
System_Time.wMilliseconds = 0
X = SystemTimeToFileTime(System_Time, Local_Time)
X = LocalFileTimeToFileTime(Local_Time, File_Time) ' 轉(zhuǎn)換成可用的類型
Handle = CreateFile(Filename, GENERIC_WRITE, FILE_SHARE_READ Or _
FILE_SHARE_WRITE, ByVal 0&, OPEN_EXISTING, 0, 0) ' 打開文件
X = SetFileTimeWrite(Handle, File_Time, ByVal 0&, ByVal 0&) ' 設(shè)置日期
CloseHandle Handle ' 關(guān)閉文件
End Function
圖三顯示的是數(shù)據(jù)庫的真實“創(chuàng)建日期”以及經(jīng)程序二偽裝的操作系統(tǒng)級的“假象”日期。

可以看出，隱藏“創(chuàng)建日期”的方法對破譯者來說只是增大了破譯的工作量，增加了破解試驗的次數(shù)。只有將該方法與下述的“方法二”相結(jié)合，才能達到“既治標又治本”的效果。不過在一般的情況下“方法一”已夠用，因為如果破譯者起始使用的測試日期與最終的真實日期相差百年，他需要付出數(shù)萬次的努力！
2、使用用戶級安全機制
通過設(shè)置不同的用戶帳號和組帳號對數(shù)據(jù)庫中的各種資源進行權(quán)限管理。這種加強了的安全機制雖然給日常使用（尤其是單用戶使用）帶來了不便，但在有安全隱患的地方依然有設(shè)置的必要。
設(shè)置各種帳號及相應(yīng)權(quán)限的簡單方法是使用“設(shè)置安全機制向?qū)?rdquo;（見圖四）。圖四還顯示了安全機制啟動后要求用戶登錄的畫面。

三、結(jié)論
所謂“道高一尺魔高一丈”，因為這世上并沒有絕對的安全。上述方法一的目的是提高破譯的成本以達到常人難以接受的程度；而方法二的初衷是增加密碼的數(shù)量。兩種方法的結(jié)合足以使破譯者望而卻步。不過這并不意味著百分之百的安全。但從思想上提高安全意識，防患于未然，這畢竟是正確的選擇。

分享：如何判斷一個字段是否在表中
'判斷一個字段是否在表中 Function BlnField(sTblName As String, sFldName As String) As Boolean 'sTblName 源表名 '要查找的字段名 Dim fld As Field Dim rs As DAO.Recordset BlnField = False Set rs = CurrentDb.OpenRecordset(sTblName) rs.Fields.Re