Q190607: PRB: DataEnvironment: DataReport Moves Form To EOF

Article: Q190607
Product(s): Microsoft Visual Basic for Windows
Version(s): 
Operating System(s): 
Keyword(s): kbGrpDSVBDB
Last Modified: 09-JAN-2000

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The information in this article applies to:

- Microsoft Visual Basic Enterprise Edition for Windows, version 6.0 
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SYMPTOMS
========

When you have a DataReport and Form with controls bound to the same
DataEnvironment, opening the report causes the form to be blank.

CAUSE
=====

When the report steps through the records, it is moving the current position for
the DataEnvironment and stops when it reaches EOF (end-of- file). This becomes
the current position for the form, which displays blank fields.

RESOLUTION
==========

- Open a second copy of the DataEnvironment in code and set the DataReport's
  DataSource property to this variable instead of the global DataEnvironment
  object.

-or-

- Reset the record pointer from a timer event.

STATUS
======

This behavior is by design.

MORE INFORMATION
================

Steps to Reproduce Behavior
---------------------------

1. Create a new Visual Basic EXE project and add a form (Form1), DataEnvironment
  (DataEnvironment1), and DataReport (DataReport1).

2. In the DataEnvironment designer, add a connection (Connection1) to a
  database, such as Microsoft SQL Server.

3. Off the connection, create a command (Command1) that selects records from a
  table, such as SELECT * FROM Authors.

4. Save the DataEnvironment.

5. In the DataReport designer, set the following properties:

        DataSource: DataEnvironment1
        DataMember: Command1

6. Add some fields from the table and save the report.

7. Add some textboxes to the form and set the following properties:

        DataSource: DataEnvironment1
        DataMember: Command1
        DataField: choose from the fields in the table

8. Run the project. The form opens and displays the first record in the table.

9. Close the form and add the following code to it:

        Option Explicit

        Sub Form_Load ()
          DataReport1.Show
        End Sub

10. Run the project again. The DataReport opens and shows the records. When you
  switch to the form, it is blank. The DataReport has moved the cursor to the
  EOF position, so the form has not record to display.

Workaround 1
------------

1. Modify the form code as follows:

        Option Explicit

        Sub Form_Load ()
          Dim de As DataEnvironment1
          Set de = New DataEnvironment1
          Set DataReport1.DataSource = de
           DataReport1.Show
        End Sub

2. Run the project. The form is now correctly positioned to the first record
  because the DataReport is using a different instance of the DataEnvironment.

Workaround 2
------------

1. Add a Timer (Timer1) to the form and set the Interval property to 0.

2. Modify the form code as follows:

        Option Explicit

        Sub Form_Load ()
          DataReport1.Show
          Timer1.Interval = 1
        End Sub

        Sub Timer1_Timer ()
          DataEnvironment1.rsCommand1.MoveFirst
          Timer1.Interval = 0
        End Sub

3. Run the project. The form is now correctly positioned to the first record.
  The timer event does not fire until the DataReport has finished stepping
  through the records and so safely resets the record pointer. This does not
  affect the DataReport.

Additional query words: kbDSupport kbdse kbvbp600 kbVBp kbDataBinding

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Keywords          : kbGrpDSVBDB 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB600Search kbVB600
Issue type        : kbprb

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