Select data from an ODBC connection into a MS Access database

Question

A little background first. Where I work we have limited access to programming tools. We have access to the Microsoft Office Suite and therefore most of our projects are created in Access even though there are better solutions out there. We recently received access to Visual Studio 2013 and I am interested in converting some of our more heavily used tools into VB.NET projects.

I have a good understanding of VBA after using it for so many years, however, converting to VB.NET is definitely a change and although I understand the concept of it, many of the functions I used in the past do not exist in VB.NET.

Which leads me to the following question.

How do I connect to one database, an ODBC connection, then put selected fields from a table in that database to a table in a Microsoft Access database?

Here is my current code.

Imports System.Data.Odbc
Imports System.Data.Odbc.OdbcCommand
Imports System.Data.OleDb

Public Class Form1

    Dim conn As OdbcConnection
    Dim connBE As OleDb.OleDbConnection

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load
        Call Connect_SLICWave()
        Call Connect_Backend()

        Dim sqlInsert As String = "INSERT INTO tblUOCs (EIAC,LCN,ALC,UOC) SELECT DISTINCT Trim(EIACODXA),Trim(LSACONXB),Trim(ALTLCNXB),Trim(UOCSEIXC) FROM ALAV_XC"
        Dim beCmd As New OleDb.OleDbCommand(sqlInsert, connBE)

        beCmd.ExecuteNonQuery()
    End Sub

    Private Sub Connect_SLICWave()
        Dim connectionString As String

        connectionString = "Dsn=slic_wave;uid=userid;pwd=password"
        conn = New OdbcConnection(connectionString)
    End Sub

    Private Sub Connect_Backend()
        Dim connectionStringBE As String

        connectionStringBE = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\database.accdb"
        connBE = New OleDb.OleDbConnection(connectionStringBE)
    End Sub

End Class

Clearly this is not going to work. I have tried a few things based on examples on the Internet but have been unable to piece together any kind of code that works.

When using the Access database I would simply link to the tables in both the ODBC connection and the backend Access database and then I could use DoCmd to run SQL to move data as needed, however with VB.NET I don't have that luxury. Perhaps I am going about this all wrong due to my lack of knowledge with Visual Studio.

Is there a better way to accomplish my end goal? I need to be able to refer to the data in the ODBC connection and then store it somewhere so that I can output a specific dataset to the end user. Can/should I use a DataSet or DataTable? How much data can be stored in a DataSet/DataTable before the program would become unstable? The data used in this process can be quite excessive at times.

Typically the user would send the tool some criteria with 4 or 5 fields worth of data. The tool will then turn around and take that criteria to get the proper dataset from the ODBC connected database using joins on about 5 to 7 tables and returns one set of data to the user. Yes, it is a bit excessive, but that's the requirement.

I hope I am explaining this well enough without being too generic. The nature of my business prevents providing specific examples.

Sorry for being longwinded and I appreciate any effort that goes into helping me solve this issue. If there is anything that needs to be clarified please let me know and I will try to explain it more clearly.

Answer 1

Imports System.Data.OleDb

Public Class Form1

    Public con As New OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\stores\Stock.accdb")
  
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        con.Open()
        Dim sql As String = "SELECT * FROM Stock"
        Dim dt As New DataTable
        Dim cmd As New OleDbCommand(sql, con)
        Dim da As New OleDbDataAdapter(cmd)
        da.Fill(dt)
        DGV.DataSource = dt
        con.Close()
    End Sub

End Class

Answer 2

You may find it helpful to be aware that when you run a query against the Access Database Engine from a .NET application you can use ODBC references in your queries and the engine will perform the required ODBC connections for you. In effect, these are temporary "on the fly" ODBC linked tables created for that specific query.

Say we have a table named [product] in SQL Server

id  name
--  -----
 1  bacon
 2  tofu

and we can reach that SQL Server instance via an ODBC DSN named "myDb". We can reference that table from an Access query as

[ODBC;DSN=myDb].[product]

So, for example, if we want to query an Access table named [Orders]

OrderID  ProductID  Qty  Units  OrderDate
-------  ---------  ---  -----  ----------
      1          1    3  pound  2016-10-17

and pull in the product names from the SQL Server table named [product] we can do this in VB.NET:

Dim myConnectionString As String =
        "Provider=Microsoft.ACE.OLEDB.12.0;" +
        "Data Source=C:\Users\Public\Database1.accdb;"
Using conn As New OleDbConnection(myConnectionString)
    conn.Open()
    Dim sql As String =
        "SELECT p.name, o.Qty, o.Units " +
        "FROM " +
            "Orders o " +
            "INNER JOIN " +
            "[ODBC;DSN=myDb].[product] p " +
                "ON p.id = o.ProductID"
    Using cmd As New OleDbCommand(sql, conn)
        Using rdr As OleDbDataReader = cmd.ExecuteReader
            While rdr.Read
                Console.WriteLine("{0} {1}(s) of {2} ", rdr("Qty"), rdr("Units"), rdr("name"))
            End While
        End Using
    End Using
End Using

which prints

3 pound(s) of bacon

Answer 3

First of all, I need to ask about the original source for your SLICWave ODBC connection. Is it still in Access, or are you perhaps pulling from Sql Server or similar at this point? ODBC is going to pass your command statement on to the original source, and if you're using Sql Server now, instead of Access, some of the SQL syntax will change on you.

For the remainder of the question, I'll assume the SQL you have will work if executed. If it turns out you need help converting that to T-SQL for SQL Server, open a separate question limited to that specific problem.

That out of the way, I'm now going to limit my scope to this statement:

I need to be able to refer to the data in the ODBC connection and ... output a specific dataset to the end user.

What you want to do is put a DataGridView control on your form (I'll use the default DataGridView1 name for now). Then make the form code look like this:

Imports System.Data.Odbc
Imports System.Data.Odbc.OdbcCommand
Imports System.Data.OleDb

Public Class Form1

    Private Property SLICWaveConnectionString As String = "Dsn=slic_wave;uid=userid;pwd=password" 

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load
        Dim sql As String = "SELECT DISTINCT Trim(EIACODXA),Trim(LSACONXB),Trim(ALTLCNXB),Trim(UOCSEIXC) FROM ALAV_XC"
        Dim dt As New DataTable
        Using cn  As New OleDb.OleDbConnection(SLICWaveConnectionString), _
              cmd As New OleDb.OleDbCommand(sql, cn)
              da  As New OleDb.OleDbDataAdapter(cmd)

              da.Fill(dt)
        End Using
        DataGridView1.DataSource = dt
    End Sub

End Class