Changing linked table location programmatically - vba

Question

I have an Access database with a linked table in a second database, located in the same directory as the first.
I would like to copy the whole directory to a new location (for testing) and have database one still link to the table in database two, but the linkage is still to the original directory, not the new location.
I'd like to do one of two things: either
Make the link to the table in database two in such a way that the folder path is relative - that the path to database two isn't hardcoded.
or
Have a routine in Form_Load (or an autoexec macro) that checks the application.path and programmatically adjusts the linkage accordingly.

Answer 1

Thanks,
I used it succesfull, however did not use it with the recordset.
Const LnkDataBase = "C:\NorthWind.mdb"
Sub relinktables()
'Routine to relink the tables automatically. Change the constant LnkDataBase to the desired one and run the sub
Dim dbs As DAO.Database
Dim tdf As DAO.TableDef
Dim strTable As String
Set dbs = CurrentDb()
For Each tdf In dbs.TableDefs
If Len(tdf.Connect) > 1 Then 'Only relink linked tables
If tdf.Connect <> ";DATABASE=" & LnkDataBase Then 'only relink tables if the are not linked right
If Left(tdf.Connect, 4) <> "ODBC" Then 'Don't want to relink any ODBC tables
strTable = tdf.Name
dbs.TableDefs(strTable).Connect = ";DATABASE=" & LnkDataBase
dbs.TableDefs(strTable).RefreshLink
End If
End if
End If
Next tdf
End Sub

Answer 2

It can be useful to have a start-up form that allows you to browse for the back-end you want and a table of the tables that should be linked. You could iterate through the tables collection, but i think a list is slightly safer. After that, a little code is all that is needed, here is a snippet:
''Connection string with database password
strConnect = "MS Access;PWD=pw;DATABASE=" & Me.txtNewDataDirectory
Set rs = CurrentDb.OpenRecordset("Select TableName From LinkTables " _
& "WHERE TableType = 'LINK'")
Do While Not rs.EOF
''Check if the table is already linked, if it is, update the connection
''otherwise, link the table.
If IsNull(DLookup("[Name]", "MSysObjects", "[Name]='" & rs!TableName & "'")) Then
Set tdf = db.CreateTableDef(rs!TableName, dbAttachSavePWD, _
rs!TableName, strConnect)
db.TableDefs.Append tdf
Else
db.TableDefs(rs!TableName).Connect = strConnect
End If
db.TableDefs(rs!TableName).RefreshLink
rs.MoveNext
Loop

Answer 3

I used usncahill's solution and modified it for my own needs. I do not have enough reputation to vote up their solution, so if you like my additional code, please vote us both up.
I wanted a quick way to switch between two back-end databases, one containing live data and the other containing test data. So I modified the previously mentioned code as follows:
Private Sub ReplaceLink(oldLink As String, newLink As String)
Dim tbl As TableDef, db As Database
Set db = CurrentDb
For Each tbl In db.TableDefs
If InStr(tbl.Connect, oldLink) > 0 Then
tbl.Connect = Replace(tbl.Connect, oldLink, newLink)
tbl.RefreshLink
End If
Next
End Sub
Public Function ConnectTestDB()
ReplaceLink "Data.accdb", "Test.accdb"
End Function
Public Function ConnectLiveDB()
ReplaceLink "Test.accdb", "Data.accdb"
End Function
Public Function TestDBSwitch()
Dim tbl As TableDef, db As Database
Dim wasData As Boolean
Dim wasTest As Boolean
wasData = False
wasTest = False
Set db = CurrentDb
For Each tbl In db.TableDefs
If InStr(tbl.Connect, "JGFC Flooring Data") > 0 Then
wasData = True
ElseIf InStr(tbl.Connect, "JGFC Flooring Test") > 0 Then
wasTest = True
End If
Next
If wasData = True And wasTest = True Then
MsgBox "Data Mismatch. Both Test and Live Data are currently linked! Connecting all tables to Test database. To link to Live database, please run again.", , "Data Mismatch"
ConnectTestDB
ElseIf wasData = True Then
ConnectTestDB
MsgBox "You are now connected to the Test database.", , "Connection Changed"
ElseIf wasTest = True Then
ConnectLiveDB
MsgBox "You are now connected to the Live database.", , "Connection Changed"
End If
End Function
(The previous code assumes that both the Test and Live Data files are located in the same directory and the file name ends in Test and Data, but can be easily modified to other paths/filenames)
I call TestSwitchDB from a button in my front-end DB to quickly change between testing and production environments. My Access DB has user controls to switch between user environments, so when the admin user logs in to the front-end DB, I use the ConnectTestDB function directly to default the admin user to connect to the test DB. I likewise, use the ConnectLiveDB function when other users login to the front-end.
There is also a quick error detection in the TestSwitchDB function to tell me if there are a mix of connections to both environments prior to calling the switch function. If this error is recurrent, it could be a sign of other issues.

Answer 4

Our corporate IT changed the pathing our shared files from local to corporate, which necessitated redirecting all of our database tables. This would have a been pain, to delete and recreate all the links, especially with multiple different databases linked. I found this question but neither of the other answers worked well for me. The following is what I used. Note, this will take awhile with many tables as each update might take a few seconds.
Public Sub Fix_Table_Locations()
Dim tbl As TableDef, db As Database, strConnect As String
Set db = CurrentDb
For Each tbl In db.TableDefs
If InStr(tbl.Connect, "Portion of connect string to change") > 0 Then
tbl.Connect = Replace(tbl.Connect, "Portion of connect string to change", "New portion of connect string")
tbl.RefreshLink
End If
Next
End Sub

Answer 5

You may be able to use a relative path depending on where the files are located. The default location where Access looks is in Documents (C:\Users\UserName\Documents). So if you enter .. then it will take you one folder up from Documents, which is the user's folder. For example if your database file will always be stored at
C:\Users\UserName\Access App\Access Database
Then you can enter "..\Access App\Database" as the relevant file location. Otherwise you have to use VBA. In my case the file/file folders may not always be in the same location, some users may store the files on their Google drive, while others may use My Documents or the desktop. I was able to use a function similar to what usncahill posted:
Sub relinkBackendDB()
Dim sFilePath As String
Dim connectionString As String
Dim tbl As TableDef
Dim db As Database
sFilePath = (Application.CurrentProject.Path & "\system\Dojo Boss Database.accdb")
connectionString = ("MS Access;PWD=MyPassword;DATABASE=" & sFilePath)
Set db = CurrentDb
For Each tbl In db.TableDefs
If Len(tbl.Connect) > 0 Then
'MsgBox tbl.Connect 'If you're getting errors, uncomment this to see connection string syntax
tbl.Connect = connectionString
tbl.RefreshLink
End If
Next
End Sub
I call this function via the on_load event procedure when my "Home" form loads up, so it gets called whenever the app is first loaded/opened. This way it will always look in the relevant file folder, no matter what the user name is.