Reputation:

MS Access linked to SQL server views

we have an issue with an access database we are upgrading to use SQL Server as its data store.

This particular database links to 2 sql databases, so I thought to simplify things, we have a view in the main database that linked to each table in the secondary database. That way access would only need to talk directly with one SQL database.

When we linked access to the database views we choose which fields were the primary keys so the views were not readonly. We have standard code that refreshes all links when a database opens to pickup any changes and the linked views become readonly because the primary key information is lost.

Is there a way of refreshing the links to views while retaining the primary key information?

John

Upvotes: 4

Answers (3)

David Walker

Reputation: 1506

I have included my entire ODBC Reconnect function below. This function is predicated with the idea that I have a table called rtblODBC which stores all of the information I need to do the reconnecting. If you implement this function, you will NOT need to worry about connecting to multiple SQL databases, as that is handled smoothly with each table to be reconnected having its own connection string.

When you get towards the end you will see that I use DAO to recreate the primary keys with db.Execute "CREATE INDEX " & sPrimaryKeyName & " ON " & sLocalTableName & "(" & sPrimaryKeyField & ")WITH PRIMARY;"

If you have any questions, please ask.

Public Function fnReconnectODBC( _
    Optional bForceReconnect As Boolean _
    ) As Boolean
    ' Comments  :
    ' Parameters: bForceReconnect -
    ' Returns   : Boolean -
    ' Modified  :
    ' --------------------------------------------------'

    On Error GoTo Err_fnReconnectODBC

    Dim db As DAO.Database
    Dim rs As DAO.Recordset
    Dim tdf As DAO.TableDef
    Dim sPrimaryKeyName As String
    Dim sPrimaryKeyField As String
    Dim sLocalTableName As String
    Dim strConnect As String
    Dim varRet As Variant

    Dim con As ADODB.Connection
    Dim rst As ADODB.Recordset
    Dim sSQL As String

    If IsMissing(bForceReconnect) Then

        bForceReconnect = False

    End If

    sSQL = "SELECT rtblODBC.LocalTableName, MSysObjects.Name, MSysObjects.ForeignName, rtblODBC.SourceTableName, MSysObjects.Connect, rtblODBC.ConnectString " _
         & "FROM MSysObjects RIGHT JOIN rtblODBC ON MSysObjects.Name = rtblODBC.LocalTableName " _
         & "WHERE (((rtblODBC.ConnectString)<>'ODBC;' & [Connect]));"

    Set con = Access.CurrentProject.Connection
    Set rst = New ADODB.Recordset

    rst.Open sSQL, con, adOpenDynamic, adLockOptimistic

        'Test the recordset to see if any tables in rtblODBC (needed tables) are missing from the MSysObjects (actual tables)
        If rst.BOF And rst.EOF And bForceReconnect = False Then

            'No missing tables identified
            fnReconnectODBC = True

        Else

            'Table returned information, we don't have a perfect match, time to relink
            Set db = CurrentDb
            Set rs = db.OpenRecordset("rtblODBC", dbOpenSnapshot)

                'For each table definition in the database collection of tables
                For Each tdf In db.TableDefs

                    'Set strConnect variable to table connection string
                    strConnect = tdf.Connect

                    If Len(strConnect) > 0 And Left(tdf.Name, 1) <> "~" Then

                        If Left(strConnect, 4) = "ODBC" Then

                            'If there is a connection string, and it's not a temp table, and it IS an odbc table
                            'Delete the table
                            DoCmd.DeleteObject acTable, tdf.Name

                        End If

                    End If

                Next

                'Relink tables from rtblODBC
                With rs

                    .MoveFirst

                    Do While Not .EOF

                        Set tdf = db.CreateTableDef(!localtablename, dbAttachSavePWD, !SourceTableName, !ConnectString)

                        varRet = SysCmd(acSysCmdSetStatus, "Relinking '" & !SourceTableName & "'")

                        db.TableDefs.Append tdf
                        db.TableDefs.Refresh

                        If Len(!PrimaryKeyName & "") > 0 And Len(!PrimaryKeyField & "") > 0 Then

                            sPrimaryKeyName = !PrimaryKeyName
                            sPrimaryKeyField = !PrimaryKeyField
                            sLocalTableName = !localtablename

                            db.Execute "CREATE INDEX " & sPrimaryKeyName & " ON " & sLocalTableName & "(" & sPrimaryKeyField & ")WITH PRIMARY;"

                        End If

                        db.TableDefs.Refresh

                        .MoveNext

                    Loop

                End With

            subTurnOffSubDataSheets

            fnReconnectODBC = True

        End If

    rst.Close
    Set rst = Nothing

    con.Close
    Set con = Nothing


Exit_fnReconnectODBC:

    Set tdf = Nothing
    Set rs = Nothing
    Set db = Nothing

    varRet = SysCmd(acSysCmdClearStatus)

    Exit Function

Err_fnReconnectODBC:

    fnReconnectODBC = False

    sPrompt = "Press OK to continue."
    vbMsg = MsgBox(sPrompt, vbOKOnly, "Error Reconnecting")
    If vbMsg = vbOK Then

        Resume Exit_fnReconnectODBC

    End If

End Function

Upvotes: 4

Jim

Reputation:

This works a litte better for me (note the moved end if's):

Dim dbCurrent As Database
Set dbCurrent = CurrentDb()

StatusList.SetFocus
StatusList.AddItem ("starting... ")
I = DoEvents()
Dim tdfCurrent As DAO.TableDef
For Each tdfCurrent In dbCurrent.TableDefs
   If Len(tdfCurrent.Connect) > 0 Then
      If Left$(tdfCurrent.Connect, 5) = "ODBC;" Then
         strCon = "ODBC;DRIVER={sql server};" & _
           "SERVER=" & ServerName & ";" & _
           "DATABASE=" & DatabaseName & ";" & _
           "UID=" & UserID & ";" & _
           "PWD=" & USERpw & ";" & _
           "APP=Microsoft Office 2003;" & _
           "WSID=" & WSID & ";"

           StatusList.AddItem ("fixing " & tdfCurrent.Name)
        tdfCurrent.Connect = strCon
        tdfCurrent.RefreshLink
     End If
  End If
  I = DoEvents()
Next tdfCurrent

  StatusList.AddItem ("----Done.")

The ODBC check is correct, even though the "ODBC;" part doesn't show in the MSysObjects view.

Upvotes: 0

Albert D. Kallal

Reputation: 49319

A good deal of DSN less code that re-links access tables to SQL server often deletes the links first, then recreates the link. The code then sets up the connection string. Thus, it is the deleting that causes you to lose what the primary key was/is.

I actually recommend that you modify your re-link code as to not delete the table links.

Try something like:

For Each tdfCurrent In dbCurrent.TableDefs
   If Len(tdfCurrent.Connect) > 0 Then
      If Left$(tdfCurrent.Connect, 5) = "ODBC;" Then
         strCon = "ODBC;DRIVER={sql server};" & _
           "SERVER=" & ServerName & ";" & _
           "DATABASE=" & DatabaseName & ";" & _
           "UID=" & UserID & ";" & _
           "PWD=" & USERpw & ";" & _
           "APP=Microsoft Office 2003;" & _
           "WSID=" & WSID & ";"
        End If
     End If
     tdfCurrent.Connect = strCon
     tdfCurrent.RefreshLink
  End If
Next tdfCurrent

Upvotes: 1

MS Access linked to SQL server views

Answers (3)

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