VB.net connection string works, then doesn't, then does - why? - vb.net

Question

Using VB.NET, VS 19 v16.10.4
I have a small application which asks a user to provide database server, database name and then builds a connection string. Then, using a data access layer DLL I've written it runs a check to see if a connection can be made to the database.
The problem is unusual:
If I write the connection string direct to the data access layer into a variable it connects;
If I use a string builder to build the string then pass it to the data access layer it fails;
If I write the connection string into a variable then pass it to the data access layer it fails;
If I use the first step again it works.
With DAL
MessageBox.Show("Using hard-coded string")
.ConnectionString = "data source=THEWINELIBRARY\MSSQLSERVER01;initial catalog=TrialDatabase;trusted_connection=true"
.DoConnectionCheck() 'THIS WORKS
MessageBox.Show("Using string builder string")
.ConnectionString = SBConnString.ToString.Trim
.DoConnectionCheck() 'THIS FAILS
MessageBox.Show("Using CS string")
.ConnectionString = CS.Trim
.DoConnectionCheck() 'THIS FAILS
MessageBox.Show("Using hard-coded string")
.ConnectionString = "data source=THEWINELIBRARY\MSSQLSERVER01;initial catalog=TrialDatabase;trusted_connection=true"
.DoConnectionCheck() 'THIS WORKS
End With
The data access layer does the following in the DoConnectionCheck method:
Public Sub DoConnectionCheck()
OpenConnection()
With AppConnection
If (.State = ConnectionState.Open) Then
RaiseEvent ConnectionOpened()
CloseConnection()
End If
End With
End Sub
and the OpenConnection method:
Private Sub OpenConnection()
With AppConnection
'Is the conenction currently closed?
If (.State = ConnectionState.Closed) Then
Try
'Set connection string to POS
.ConnectionString = ConnectionString
'Try opening the connection
.Open()
'Otherwise raise an event.
Catch E As Exception
RaiseEvent ConnectionFailed()
End Try
End If
End With
End Sub
And the connection string is a simple property:
Public ConnectionString As String
So, what I don't understand is why the connection fails with the string builder string and the variable string, but not with the hard-coded string?
If there is any other code you need please let me know, I posted what i think is enough to explain the problem without putting in too much that makes the question unreadable.
here is the code which constructs the connection string from entries in a form:
Dim CS As String = "datasource=" & .TextServer.Text.Trim & ";initial catalog=" & .TextDatabase.Text.Trim & ";trusted_connection=true"
SBConnString = New StringBuilder
With SBConnString
.Clear()
.Append("datasource=")
.Append(Me.TextServer.Text.Trim)
.Append(";initial catalog=")
.Append(Me.TextDatabase.Text.Trim)
.Append(";trusted_connection=true")
End With
When these strings are compared to the hard coded string
DAL.ConnectionString = "data source=THEWINELIBRARY\MSSQLSERVER01;initial catalog=TrialDatabase;trusted_connection=true"
the function returns a value 1, "The first substring follows the second substring in the sort order." according to the documentation.
As far as I can see, these strings are identical but somewhere an additional character must be getting inserted in the form textbox.
Again, any suggestions gratefully received.
All the best,
Dermot

Answer 1

Mea culpa - I had a very simple mistake which I could not see - in the two strings causing the problem I had datasource rather than date source...