Question

我一直在寻找答案，因为有很多类似的问题，但没有找到这个特殊情况。

我有一个SQL服务器和一个访问文件（前端）。此Access文件具有与SQL Server链接的链接表，每次尝试打开一个表时，都会出现一个询问用户和密码的提示。

好的，这是完美的，因为它（几乎）是我想要的行为。

此外，还有一个本地表，其中包含加密密码的用户/密码。每次用户打开文件时，他/她的传递都会被解密，我想打开一个连接，因此链接表不会要求传递。

有人知道如何编码此连接吗？

提前致谢！

Answer 1

我认为你想要的是"DSN-LESS connection"。我过去做过类似的事。基本上，在用户登录时，您使用基于用户凭据构建的连接字符串重新链接表。

有关详细信息，请先查看此SO Question。

此外，以下是我过去使用的一些例程，您可以自由使用\ modify。从您的登录过程中调用这些。

Public Function RelinkDSNTables( _
      ByVal ServerName As String, _
      ByVal DatabaseName As String, _
      ByVal UserName As String, _
      ByVal Password As String) As Boolean
On Error GoTo Err_Handler

Dim dsn As String
dsn = GetDSNLink(ServerName, DatabaseName, UserName, Password)
Dim td As TableDef
Dim db As DAO.Database
Set db = CurrentDb
Dim rst As ADODB.Recordset

'Get a list of tables that need to be relinked'
If GetLocalRecordSet(rst, "SELECT * FROM TableMapping") < 1 Then
   Err.Raise 1000, "Missing Tables!", "Missing Table Mappings!"
End If

Dim fNeedToRefresh As Boolean

'See if we actually need to relink the tables'
For Each td In db.TableDefs
   If td.Connect <> vbNullString Then
      If td.Connect <> dsn Then
         fNeedToRefresh = True
         Exit For
      End If
   End If
Next td

If fNeedToRefresh = False Then
   RelinkDSNTables = True
   GoTo Err_Handler
End If

'Drop linked table in Access'
For Each td In CurrentDb.TableDefs
   If td.Connect <> vbNullString Then
      CurrentDb.TableDefs.Delete td.Name
   End If
Next td

'Create new linked table using new DSN'
rst.MoveFirst
Do Until rst.EOF
   Set td = db.CreateTableDef(rst!LocalTableName, dbAttachSavePWD, rst!RemoteTableName, dsn)
   db.TableDefs.Append td
   rst.MoveNext
Loop

'Because I am paranoid, refresh the link'
db.TableDefs.Refresh
For Each td In db.TableDefs
   If td.Connect <> "" Then td.RefreshLink
Next td

RelinkDSNTables = True

Err_Handler:
   If Err.Number = 3011 Then
      'Happens if user does not have permission in SQL Server; Nothing to see here, move along'
      Err.Clear
      Resume Next
   ElseIf Err.Number = 3010 Then
      'already exists; should not occur, but if it does eat the exception and move on'
      Err.Clear
      Resume Next
   ElseIf Err.Number <> 0 Then
      Err.Raise Err.Number, Err.Source, Err.Description
   End If
End Function

Private Function GetDSNLink( _
      ByVal ServerName As String, _
      ByVal DatabaseName As String, _
      ByVal UserName As String, _
      ByVal Password As String) As String
On Error GoTo Err_Handler

If ServerName = "" Or DatabaseName = "" Then
   Err.Raise -1220, "Missing Server \ DB", _
      "Unable to refresh table links because you are missing the server or database name!"
End If

Dim dsnLink As String

If UserName = "" Then
   'trusted connection'
   dsnLink = "ODBC;DRIVER=SQL Server;SERVER=" & ServerName & _
            ";DATABASE=" & DatabaseName & ";Trusted_Connection=Yes"
Else
   'MixedMode connection'
     '//WARNING: This will save the username and the password with the linked table information.
   dsnLink = "ODBC;DRIVER=SQL Server;SERVER=" & ServerName & _
            ";DATABASE=" & DatabaseName & ";UID=" & UserName & ";PWD=" & Password
End If

GetDSNLink = dsnLink

Err_Handler:
   If Err.Number <> 0 Then
      Err.Raise Err.Number, Err.Source, Err.Description
   End If
End Function

编辑：添加了示例GetLocalRecordSet功能

Public Function GetLocalRecordSet(ByRef rs As ADODB.Recordset, ByVal sql As String) As Long
On Error GoTo Err_Handler

If sql = vbNullString Then
   Err.Raise vbObjectError + 1001, _
      "Empty SQL String", "Empty SQL String Passed to GetLocalRecordset Function!"
End If

Set rs = New ADODB.Recordset

rs.Open sql, CurrentProject.Connection, adOpenKeyset, adLockOptimistic

If rs Is Nothing Then
   GetLocalRecordSet = -1
   GoTo Err_Handler
End If

If rs.State = adStateOpen Then
   If Not rs.EOF Then
      rs.MoveLast
      GetLocalRecordSet = rs.RecordCount                 'store number of records
      rs.MoveFirst
   Else
      GetLocalRecordSet = 0
   End If
Else
   GetLocalRecordSet = -2
End If

Err_Handler:
   If Err.Number <> 0 Then
      Err.Raise Err.Number, Err.Source, Err.Description
   End If
End Function

Answer 2

您可以使用存储在本地表中的用户名/密码编写代码以编程方式连接到SQL数据库。这应该在Access app load上发生（例如，使用Autoexec宏）。

您可以在此处阅读有关Autoexec宏的信息：http://www.vb123.com/toolshed/05_map/ch04_autoexec.htm

所以，你会有一个功能，例如在应用程序启动时从Autoexec宏调用的OpenConnection（）。任何后续的表格开头都不应提示输入密码。

我不确定这是否适用于SQL后端。希望它会。

用于打开链接表的连接字符串Access - ＆gt; SQL服务器（vba）

2 个答案: