HOWTO: Extract Multiple RDO Resultsets from Stored Procedures

ID: Q154825

The information in this article applies to:

Microsoft Visual Basic Learning, Professional, and Enterprise Editions for Windows, version 6.0
Microsoft Visual Basic Professional and Enterprise Editions for Windows, version 5.0
Microsoft Visual Basic Enterprise Edition, 32-bit only, for Windows, version 4.0

SUMMARY

SQL Server stored procedures are capable of returning more than one recordset and the Remote Data Object (RDO) has the ability to access these Multiple Resultsets.

When calling these stored procedures, the following error can be encountered:

Error 40002

"37000: [Microsoft][ODBC SQL Server Driver][SQL Server]Cannot open a cursor on a stored procedure that has anything other than a single
select statement in it"

The following code sample showing how to return the multiple Resultsets using the MoreResults Property of the RDO.

MORE INFORMATION

There are two methods to avoid Error 40002.

Method 1

Use The ODBC Cursor library rather than Server Side Cursors. To do this, use the following code:


   rdoEngine. rdoDefaultCursorDriver = rdUseODBC

- or -


   rdoEnvironments(0).CursorDriver = rdUseOdbc

This option gives better performance for small result sets, but may degrade quickly for larger result sets depending on the Server and workstation configuration.

NOTE: If you are using SQL text fields, you must use Server-side cursors to bypass Error 40002"

Method 2

Use Server Side Cursors, a Forward Only Cursor, and a rowset size of 1. Make the server create a cursor-less resultset on the server side by using a forward only cursor and a RowSetSize of 1.

The following code sample illustrates how to create a stored procedure that returns multiple result sets using method 2.

Create the stored procedure on SQL Server:
1. Start the ISQL utility that shipped with SQL server.
2. Connect to your SQL server.
3. Select the pubs database from the combo box labeled DB.
4. Enter the following lines into the Query Tab:
```
      CREATE PROCEDURE TestMultiResults AS
      select * from authors
      select * from discounts
      GO
  
```
5. Choose the Query|Execute menu. The Results tab should display:
  
  This command did not return data, and it did not return any rows
  
  A stored procedure called TestMultiResults has now been created in the pubs database on SQL Server.

Create the Visual Basic client to call the stored procedure:

Start Visual Basic. Form1 is created by default.

Add a Command Button (Command1) and a List Box (List1) to Form1.

Add the following code to Form1:


      Private Sub Form_Load()
         Command1.Caption = "Run Stored Procedure"
      End Sub

       Private Sub Command1_Click()
        Dim cn As rdoConnection
        Dim ps As rdoPreparedStatement
        Dim rs As rdoResultset
        Dim strConnect As String
        'set cursor driver to use server-side cursors
        rdoDefaultCursorDriver = rdUseServer

        'open a connection to the pubs database using DSNless connections
        'replace myServer with the name of your SQL server

        strConnect = "Driver={SQL Server}; Server=myServer; " & _
                     "Database=pubs; Uid=sa; Pwd="
        Set cn = rdoEnvironments(0).OpenConnection(dsName:="", _
                                              Prompt:=rdDriverNoPrompt, _
                                              ReadOnly:=False, _
                                              Connect:=strConnect)

        'create a prep stmt for the stored proc call
        Set ps = cn.CreatePreparedStatement("MyPs", _
                                            "{call TestMultiResults}")
        'set the RowSet size to 1
         ps.RowsetSize = 1

         'open the resultset with forward-only cursor
         Set rs = ps.OpenResultset(rdOpenForwardOnly)

         'add the first resultset to a list box
         While Not rs.EOF
             list1.AddItem rs("au_fname") & " " & rs("au_lname")
             rs.MoveNext
         Wend

         'move to the second resultset
         rs.MoreResults
         list1.AddItem "Second Resultset Below"
         'add the second resultset to the same list box
         While Not rs.EOF
             list1.AddItem rs("discounttype") & " = " & rs("discount")
             rs.MoveNext
         Wend

         'Close the resultset and the connection and set both to nothing
         rs.Close
         Set rs = Nothing
         cn.Close
         Set cn = Nothing
      End Sub

Run the project and click the "Run Stored Procedure" button. You should see a list of Authors and then Discounts in the list box.

REFERENCES

For more information, please see the following articles in the Microsoft Knowledge Base:

Q147875 HOWTO: Use "DSN-Less" ODBC Connections with RDO and DAO

Q147814 HOWTO: Retrieve Multiple Result Sets from a Stored Procedure

Q149054 INFO: Choosing a rdoResultset Cursortype

Additional query words: kbVBp400 kbVBp500 kbVBp600 kbdse kbDSupport kbRDO kbVBp

Keywords : kbRDO kbVBp kbVBp400 kbVBp500 kbVBp600 kbGrpVBDB kbDSupport
Version : WINDOWS:4.0,5.0,6.0
Platform : WINDOWS
Issue type : kbhowto