PRB: Default Property of Dynaset Different in VB 4.0

   Dim ds as Dynaset
   Data1.RecordSource = ds
				

   Dim ds as Dynaset
   Data1.RecordSource = ds.Name
				

MORE INFORMATION

Steps to Reproduce

1. Start Visual Basic.
2. On the File menu, click New Project.
3. Double-click the data control button in the Toolbox to add a new data control, named Data1, to the form.
4. Add a command button to the form by clicking the command button icon in the Toolbox.
5. Insert the following code in the Command1_Click procedure, changing the path with the OpenDatabase statement to refer to where your copy of BIBLIO.MDB is located. In addition, because the code below uses old style syntax, when running under Visual Basic 4.0 you must have "Microsoft DAO 2.5/3.0 Compatibility Layer" checked in the References dialog box.

         Sub Command1_Click ()
             Dim db As Database
             Dim ds As Dynaset
   
             Set db = OpenDatabase("c:\vb\biblio.mdb")
             Set ds = db.CreateDynaset("Authors")
             'set Data1's RecordSource to the Name of the ds object
             'works with Visual Basic 3.0, doesn't work with Visual Basic 4.0
             Data1.RecordSource = ds
         End Sub
   						

6. On the Run menu, click Start (ALT, R, S) or press F5. When compiled under Visual Basic 3.0, the above code works as expected and Data1.RecordSource has the value "Authors" when the procedure exits. With Visual Basic 4.0, the program fails to run and flags the last line in the procedure with a 'Type mismatch' error. Changing the last line from

         Data1.RecordSource = ds
   						

   to the following

         Data1.RecordSource = ds.Name
   						

   resolves the problem.

The RecordSource property of a data control expects a string value, and that is what is returned as the default property of a dynaset in Visual Basic 3.0. In Visual Basic 4.0, referring to a dynaset by its name only is interpreted to mean that you are referring to the recordset object itself. Because RecordSource expects a string, Visual Basic raises the "Type mismatch" error when an attempt is made to assign a recordset object to RecordSource.

NOTE: The Name property of a dynaset or recordset object refers to the name of the table, QueryDef, or SQL statement used to create it (see the online help for Name).