How To Use "DSN-Less" ODBC Connections with RDO

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With Microsoft Visual Basic versions listed above, you can specify yourODBC driver and server in your connect string when using RDO (Remote DataObjects) and DAO (Data Access Objects). This eliminates the need to set upa DSN (Data Source Name). This is called a "DSN-Less" ODBC connectionbecause you do not need to set up a DSN in order to access your ODBCdatabase server.

To do this, you specify a "driver=" parameter in your connect property.The following three examples show how this is done with the SQL Server,Access, and Oracle ODBC drivers:
   'Microsoft SQL Server ODBC Driver example    cnstr = "driver={SQL Server};server=myserver;" & _      "database=pubs;uid=<username>;pwd=<strong password>"   cn.Connect = cnstr   'Microsoft Access ODBC Driver example (version 2.x)   cnstr = "Driver={Microsoft Access Driver (*.mdb)};" & _     "Dbq=c:\program files\devstudio\vb\biblio.mdb;" & _     "Uid=Admin; Pwd="   cn.Connect = cnstr   'Microsoft ODBC Driver for Oracle example   cnstr = "Driver={Microsoft ODBC Driver for Oracle};" & _    "; Uid=demo; Pwd=demo"   ' Note that 1.0 version of the Microsoft  Oracle driver used   ' "ConnectString" notation instead of "Server"				

NOTE: The driver name must be surrounded by curly brackets. For example:
"{SQL Server}"

The following information is taken from Visual Basic Books Online:
The connect string contains a series of semi-colon-delimited arguments as defined by the ODBC interface - including the ODBC driver itself. That is, all ODBC drivers have specific argument requirements so you should consult the documentation included with the driver for specific information. This connect string is passed to the ODBC API SQLDriverConnect function along with the hEnv for the associated rdoEnvironment object.
If you do want to set up a DSN, you can use the following methods:
  • Manually with the ODBC Admin utility(Odbcad32.exe).
  • Through code with the RDO rdoRegisterDataSource method.
  • Through code with the DAO RegisterDatabase method.
  • Through code with the ODBC API SQLConfigDatasource API function.

Sample Program

The following RDO example uses a "DSN-less" ODBC connection so you do notneed to set up a DSN with the ODBC Admin utility beforehand.
  1. Start a new project in Visual Basic. Form1 is created by default.
  2. Add a CommandButton to Form1, Command1 by default.
  3. Paste the following code into the code window of Form1.

    Note You must change UID =<username> and PWD =<strong password> to the correct values before you run this code. Make sure that UID has the appropriate permissions to perform this operation on the database.
          Private Sub Command1_Click()        Dim Cn As New rdoConnection           'creatable rdoConnection        Dim Qr As New rdoQuery                'creatable rdoQuery        Dim Rs As rdoResultset                'pointer to rdoResultset        Dim cnstr As String                   'hold connection info        cnstr = "driver={SQL Server};server=myserver;" & _          "database=pubs;uid=<username>;pwd=<strong password>"        Cn.Connect = cnstr        Cn.CursorDriver = rdUseClientBatch        Cn.EstablishConnection Prompt:=rdDriverNoPrompt        Set Qr.ActiveConnection = Cn        Qr.SQL = "Select * From Authors"        Set Rs = Qr.OpenResultset(Type:=rdOpenKeyset, _          LockType:=rdConcurBatch)        Debug.Print Rs(0), Rs(1), Rs(2)      End Sub						
  4. Note that you must change your DRIVER, SERVER, DATABASE, UID, and PWD parameters in the Connect method. You also need to modify the SQL statement contained in the Command1_Click event to match your own SQL data source.
  5. Start the program or press the F5 key.
  6. Click the Command1 button to create an rdoResultset and display the first row of data in the debug window.
In Visual Basic Books Online see:
  Guide to Building Client Server Applications in Visual Basic (Enterprise)    Part 3: Data Access Options      Using Remote Data Objects and the Remote Data Control        Establishing an RDO Connection          Providing Connection Strings to RDO				

(c) Microsoft Corporation 1997, All Rights Reserved. Contributions by Jon
Fowler, Microsoft Corporation
kbVBp500 kbVBp600 kbdse kbDSupport kbVBp kbODBC KbRDO kbDriver kbDatabase kbSQL kbOracle

Article ID: 166392 - Last Review: 12/04/2015 16:44:58 - Revision: 2.1

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