Reading OleDb records into TextBox using ComboBox VB.NET - vb.net

Question

I'm new to programming. What i'm trying to accomplish is to fill in 9 textboxes in VB.NET, reading access table TblKlanten, using a combobox (CbbNaamfirma). I cannot get this to work for the life of me; i've been searching for 6 hours for this simple thing. Can any of you help me out? I've read numerous threads on SO.com like this and they all just won't work for me.
Code i have now:
Private Sub CbbNaamfirma_SelectedIndexChanged(sender As System.Object, e As System.EventArgs) Handles CbbNaamfirma.SelectedIndexChanged
Dim Connection As New OleDb.OleDbConnection
Connection.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source='" & Application.StartupPath & "\Database.accdb.'"
Try
Connection.Open()
Dim query As String
query = "SELECT Adres FROM TblKlanten WHERE [Naam firma] = ' " & CbbNaamfirma.Text & " ' "
Dim cmd As New OleDbCommand(query, Connection)
Dim Reader As OleDbDataReader = cmd.ExecuteReader
Reader = cmd.ExecuteReader
While Reader.Read
TxtAdresprev.Text = Reader.GetString("Adres")
End While
Connection.Close()
Catch ex As OleDbException
MessageBox.Show(ex.Message)
Finally
Connection.Dispose()
End Try
End Sub
Thank you in advance. Hope that code block turned out alright?

Answer 1

The first thing to change is the reading from the database using a parameterized query. Notice that your code cannot find anything because you add a space before and after the value of the combobox.
Then you need to start employing the using statement around the disposable objects to ensure a proper closing and disposing
Finally the GetString method from the OleDbDataReader wants a numeric index inside the returned list of fields, not the name of the field
Private Sub CbbNaamfirma_SelectedIndexChanged(sender As System.Object, e As System.EventArgs) Handles CbbNaamfirma.SelectedIndexChanged
Dim cnString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" & _
Application.StartupPath & "\Database.accdb"
Dim query = "SELECT Adres FROM TblKlanten WHERE [Naam firma] = ?"
Using Connection = New OleDb.OleDbConnection(cnString)
Using cmd = New OleDbCommand(query, Connection)
Try
Connection.Open()
cmd.Parameters.AddWithValue("#p1", CbbNaamfirma.Text)
Using Reader = cmd.ExecuteReader
While Reader.Read
Dim posAdres = Reader.GetOrdinal("Adres")
TxtAdresprev.Text = Reader.GetString(posAdres)
.... other text boxes for other fields here.....
End While
End Using
Catch ex As OleDbException
MessageBox.Show(ex.Message)
End Try
End Using
End Using
End Sub
Also your connection string seems to be wrong. No need of quotation and that stray point after the fielname is wrong