KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q131836: PRB: Grid Not Refreshing Displaying a Cursor From Query

Article: Q131836
Product(s): Microsoft FoxPro
Version(s): 3.00 5.00 | 3.00b
Operating System(s): 
Keyword(s): kbHWMAC kbvfp kbvfp300 kbvfp500 kbvfp600
Last Modified: 06-AUG-1999

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Visual FoxPro for Windows, versions 3.0, 5.0, 6.0 
- Microsoft Visual FoxPro for Macintosh, version 3.0b 
-------------------------------------------------------------------------------

SYMPTOMS
========

If a Grid's RecordSource property is set to a cursor and that cursor is updated
at run time by using a "SQL Select Into Cursor <CursorName>" command, the
grid does not display any data even if you Refresh it by using the
ThisForm.Refresh or ThisForm.<GridName>.Refresh command.

CAUSE
=====

When you execute a SQL Select statement into the same cursor specified in the
grid's RecordSource property, the original cursor has to be destroyed before the
new cursor can be created. When this happens, the grid columns and the
RecordSource are also cleared and then re-created. The grid's record source is
set to the new cursor, and the grid automatically creates columns. The new grid
is working from scratch, so it does not load the data from the cursor.

RESOLUTION
==========

To refresh the grid in this situation, set the Grid's RecordSource property to
itself as in this example:

      thisform.grid1.recordsource=thisform.grid1.recordsource

STATUS
======

This behavior is by design.

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

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

  Q140653 PRB: Cursor-Based Grid Goes Blank If SQL SELECT Resets Cursor

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

1. Create a form, and add the CUSTOMER.DBF table (in the \VFP\SAMPLES\DATA
  directory) to the Data Environment.

2. Place the following code in the Load event of the form: CREATE CURSOR
  Compdisp (company c(40),city c(15),country c(15))

3. Place the following code in the Destroy event of the form:

     SELECT Compdisp
     USE

4. Create a grid on the form, and give the grid the following property
  settings:

     ColumnCount=3
     RecordSourceType=Alias
     RecordSource=Compdisp

5. Add a text box to the form.

6. Add a command button with the following code in its Click event:

     SELECT company,city,country;
        FROM customer;
        WHERE customer.country=thisform.text1.value;
        INTO CURSOR Compdisp
     THISFORM.GRID1.REFRESH

7. Run the Form. Type "France" in the text box, and then click the command
  button.

The grid should display all records where Customer.Country="France," but it
doesn't. The grid is blank. THISFROM.GRID1.REFRESH does not seem to update the
grid. This happens even if the Cursor is not created in the Load event of the
Form.

To have the grid display the data correctly, place the following command as the
last line of code for the Click event of the command button:

     ThisForm.Grid1.RecordSource =ThisForm.Grid1.RecordSource

Additional query words:

======================================================================
Keywords          : kbHWMAC kbvfp kbvfp300 kbvfp500 kbvfp600 
Technology        : kbHWMAC kbOSMAC kbVFPsearch kbAudDeveloper kbVFP300bMac kbVFP300 kbVFP500 kbVFP600
Version           : 3.00 5.00 | 3.00b

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.