HOWTO: Use "DSN-Less" ODBC Connections with RDO
ID: Q166392
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The information in this article applies to:
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Microsoft Visual Basic Professional and Enterprise Editions for Windows, versions 5.0, 6.0
SUMMARY
With Microsoft Visual Basic versions listed above, you can specify your
ODBC driver and server in your connect string when using RDO (Remote Data
Objects) and DAO (Data Access Objects). This eliminates the need to set up
a DSN (Data Source Name). This is called a "DSN-Less" ODBC connection
because you do not need to set up a DSN in order to access your ODBC
database 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=sa;pwd="
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};" & _
"Server=OracleServer.world; 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.
MORE INFORMATION
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 not
need to set up a DSN with the ODBC Admin utility beforehand.
- Start a new project in Visual Basic. Form1 is created by default.
- Add a CommandButton to Form1, Command1 by default.
- Paste the following code into the code window of Form1:
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=sa;pwd="
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
- 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.
- Start the program or press the F5 key.
- Click the Command1 button to create an rdoResultset and display the
first row of data in the debug window.
REFERENCES
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
Additional query words:
kbVBp500 kbVBp600 kbdse kbDSupport kbVBp kbODBC KbRDO kbDriver
kbDatabase kbSQL kbOracle
Keywords : kbGrpVBDB
Version :
Platform : WINDOWS
Issue type : kbhowto