如何使用 Access VBA 更新所有 ODBC 链接的 SQL Server 表的服务器名称

Question

我需要能够提供一种方法来更新 Access 数据库中所有 ODBC 链接表连接中的服务器名称。所有表都已从 Access 迁移到 SQL Express 实例。需要一个选项来更新所有外部表链接以从“Localhost\SQLExpress”指向另一台服务器上的 SQL 实例。数据库名称将保持一致。只需更新服务器实例名称。

我找到了如何连接到 Access 数据库文件和 Excel 文件的示例，而不是到 SQL Server 的 ODBC 连接。这里的一篇文章指出需要标注一个 db 对象并直接使用它，而不是尝试直接使用 CurrentDb。这让我更进一步，但现在代码在尝试将新连接字符串分配给 TableDef 时因类型转换而失败。

Dim OldServer As String
Dim NewServer As String
Dim OldPath As String
Dim NewPath As String
Dim strPath As String

NewServer = Me.NewServerInstance ' get new Server Instance name from form
OldPath = GetCurrentPath("Version")
'Parse old name from the ODBC connection string
OldServer = Replace(Left(OldPath, InStr(GetCurrentPath("Version"), "UID=") - 2), "ODBC Driver 13 for SQL Server;SERVER=", "")
NewPath = Replace(OldPath, OldServer, NewServer)

If NewServer = OldServer Then
GoTo UpdateInstance_Click_Exit
Else
    'update all table connection strings. 
    'Loop & replace Old server instance with New server instance
    Dim Db As DAO.Database
    Set Db = CurrentDb
    Dim td As DAO.TableDef
    For Each td In Db.TableDefs
        If (td.Attributes And dbAttachedODBC) = dbAttachedODBC Then
            Db.TableDefs(td).Connect = NewPath 'getting a datatype conversion error here...
            Db.TableDefs(td).RefreshLink
'           MsgBox (db.TableDefs(td).Connect)
        End If
    Next
End If

代码示例是我想出的。有一条注释指示发生数据类型转换错误的位置。我想我需要知道这是否可能，或者我是否正在尝试做一些不可能的事情，或者只是以错误的方式去做......

Answer 1

我们在您调用 AttachSqlServer 时使用此代码，需要四个参数：

Public Function ConnectionString( _
    ByVal Hostname As String, _
    ByVal Database As String, _
    ByVal Username As String, _
    ByVal Password As String) _
    As String

' Create ODBC connection string from its variable elements.
' 2016-04-24. Cactus Data ApS, CPH.

    Const AzureDomain   As String = ".windows.net"
    Const OdbcConnect   As String = _
        "ODBC;" & _
        "DRIVER=SQL Server Native Client 11.0;" & _
        "Description=Application Name;" & _
        "APP=Microsoft? Access;" & _
        "SERVER={0};" & _
        "DATABASE={1};" & _
        "UID={2};" & _
        "PWD={3};" & _
        "Trusted_Connection={4};"

'    Const cstrConnect   As String = _
'        "ODBC;Driver=SQL Server Native Client 11.0;Server=(localdb)\MSSQLLocalDB;Database=Test;Trusted_Connection=Yes"

    Dim FullConnect     As String

    If Right(Hostname, Len(AzureDomain)) = AzureDomain Then
        ' Azure SQL connection.
        ' Append servername to username.
        Username = Username & "@" & Split(Hostname)(0)
    End If
    FullConnect = OdbcConnect
    FullConnect = Replace(FullConnect, "{0}", Hostname)
    FullConnect = Replace(FullConnect, "{1}", Database)
    FullConnect = Replace(FullConnect, "{2}", Username)
    FullConnect = Replace(FullConnect, "{3}", Password)
    FullConnect = Replace(FullConnect, "{4}", IIf(Username & Password = "", "Yes", "No"))

    ConnectionString = FullConnect

End Function

Public Function AttachSqlServer( _
    ByVal Hostname As String, _
    ByVal Database As String, _
    ByVal Username As String, _
    ByVal Password As String) _
    As Boolean

' Attach all tables linked via ODBC to SQL Server or Azure SQL.
' 2016-04-24. Cactus Data ApS, CPH.

    Const cstrDbType    As String = "ODBC"
    Const cstrAcPrefix  As String = "dbo_"

    Dim dbs             As DAO.Database
    Dim tdf             As DAO.TableDef
    Dim qdf             As DAO.QueryDef

    Dim strConnect      As String
    Dim strName         As String

    On Error GoTo Err_AttachSqlServer

    Set dbs = CurrentDb
    strConnect = ConnectionString(Hostname, Database, Username, Password)

    For Each tdf In dbs.TableDefs
        strName = tdf.Name
        If Asc(strName) <> Asc("~") Then
            If InStr(tdf.Connect, cstrDbType) = 1 Then
                If Left(strName, Len(cstrAcPrefix)) = cstrAcPrefix Then
                    tdf.Name = Mid(strName, Len(cstrAcPrefix) + 1)
                End If
                tdf.Connect = strConnect
                tdf.RefreshLink
                Debug.Print Timer, tdf.Name, tdf.SourceTableName, tdf.Connect
                DoEvents
            End If
        End If
    Next

    For Each qdf In dbs.QueryDefs
        If qdf.Connect <> "" Then
            Debug.Print Timer, qdf.Name, qdf.Type, qdf.Connect
            qdf.Connect = strConnect
        End If
    Next
    Debug.Print "Done!"

    AttachSqlServer = True

Exit_AttachSqlServer:
    Set tdf = Nothing
    Set dbs = Nothing
    Exit Function

Err_AttachSqlServer:
 '   Call ErrorMox
    Resume Exit_AttachSqlServer

End Function