HOWTO: Create and Implement a UserConnection

• Microsoft Visual Basic Enterprise Edition for Windows, versions 5.0, 6.0

SUMMARY

The UserConnection Designer is one of the new ActiveX Designers included with Visual Basic 5.0 and higher. It allows you to wrap SQL or a Stored Procedure with code at design time so you can call it as a method at run time. This way, Visual Basic will list the parameters of your stored procedure in the object browser just as it does with any other VBA method. This new functionality can replace the rdoPreparedStatement and rdoQuery objects, although these are still available.

The following is an excerpt on the UserConnection from Books Online:

The UserConnection designer uses Visual Basic's ActiveX designer architecture to provide design-time support for programmatic data access. It allows you to create connection and query objects at design time. These connections and queries are persisted as project-level objects. You can pre-set properties, define new properties and methods, and write code behind the objects to catch events.

MORE INFORMATION

This sample uses SQL Server and the Pubs database, but you can change the DSN, UID, PWD, and SQL to match any ODBC database you may be using.

Task One: Create the Example Stored Procedure

1. This sample SQL Server stored procedure accepts an input parameter of au_id and returns a resultset and a test output variable. The test output variable is hard-coded and has no meaning except to demonstrate how to return an output using a UserConnection. If you are not using SQL Server, you might have to modify the SQL into an acceptable format for your database server.



2. To create this stored procedure you will need a tool that allows you to execute SQL such as ISQL/W or MSQuery included with SQL Server. Select the Pubs database, then place the following Create Procedure T-SQL in the SQL window of your selected tool and execute it:

   
         Create procedure GetAuthorInfo
           @au_id Varchar(11), @testOut Varchar(10) OUTPUT As
           Select * from authors Where au_id = @au_id
           Select @testOut = 'Hello'
    

Task Two: Create the Userconnection

1. Start a new project in Visual Basic and choose "Standard EXE." Form1 is created by default.



2. From the Project menu, select Components, select the Designer tab, and then place a check next to Microsoft UserConnection.



3. From the Project menu, select Add ActiveX Designer, then select Microsoft UserConnection. This will bring up a dialog titled UserConnection1 Properties.



4. On the Connection tab, select either a DSN or a DSN-Less connection and fill in the appropriate information. If you select DSN-less, make sure you specify a database in the Other ODBC Attributes area with database=pubs. On the Authentication tab, fill in your username and password, and place a check next to Save Connection Information for Design time. On the Miscellaneous tab in the Other section, choose Use ODBC Cursor Library because you have more than one Select statement in your stored procedure.



5. Click OK to save this information, and return to the Designer window. Press the F4 key to display the Properties window and change the Name property from UserConnection1 to StoredProcs.



6. Insert a new Query by right-clicking on StoredProcs and choosing Insert Query or by clicking on the Insert Query toolbar icon. Change the name of the Query from Query1 to GetAuthorInfo. From the Source of Query, choose Based on Stored Procedure, then select the stored procedure you created earlier, GetAuthorInfo.



7. If you select the Parameters tab, you can review the input and output parameters. Your GetAuthorInfo Query setup is now finished. Click OK to close the Dialog.



8. To place code in the connection event of your UserConnection, select View Code from the UserConnection toolbar. Choose UserConnection in from the upper-left combo box, then choose the Connect Event from the upper-right combo box. Place the following code in the UserConnection Connect event:

   
         Debug.Print "Connect"
    

Task Three: The Userconnection Code

1. Add a CommandButton, Command1, to Form1 of Project1.



2. Paste the following code in the General Declarations section of Form1:

   
         Private Sub Command1_Click()
           Dim objSP As New StoredProcs             'creatable UC object
           Dim objRs As rdoResultset                'pointer to rdoResultset
           Dim lngRet As Long, strOut As String     'vars to hold output
   
           objSP.EstablishConnection rdDriverNoPrompt  'establish connection
           lngRet = objSP.GetAuthorInfo("648-92-1872", strOut) 'SP method
           Set objRs = objSP.LastQueryResults          'get results off objRs
           Debug.Print lngRet, strOut, objRs(0)        'output example results
         End Sub
    




3. Start the program or press the F5 key.



4. Click the Command1 button to execute the UserConnection code. The Stored Procedure return value, output value, and the first column of the returned resultset will print in the Debug window.

REFERENCES

In Visual Basic Books Online see:

  Guide to Building Client Server Applications in Visual Basic (Enterprise)
    Part 1: Overview
      Client/Server Tools
        The UserConnection Designer 

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Version : WINDOWS:5.0;
Platform : WINDOWS
Issue type : kbhowto