KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q178760: HOWTO: Alter the Properties of a View at Run Time

Article: Q178760
Product(s): Microsoft FoxPro
Version(s): 
Operating System(s): 
Keyword(s): kbcode kbnokeyword kbHWMAC kbvfp300 kbvfp500 kbvfp600
Last Modified: 19-AUG-1999

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

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

SUMMARY
=======

Under some circumstances, it may be desirable to modify the properties of a view
at run time. This article describes the properties and default property values
associated with a view. The sample code illustrates how to create a view and use
the DBSETPROP() function to alter the properties of the view programmatically.

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

The properties of a view created with the View Designer are readily accessible
from the View Designer. The properties of a view created programmatically,
however, use default values unless those values are changed either
programmatically or from the View Designer.

The default values of a view created programmatically are as follows:

  Property Name            Default Value
  --------------------------------------

  SendUpdates              .F. (False)
  UpdateType               1 SQL Update
  WhereType                3 Key and Modified Fields
  BatchUpdateCount         1
  UseMemoSize              255
  FetchSize                100
  FetchMemo                .T. (True)
  MaxRecords               -1 (All)
  Tables                   Database Container and Table Name
  Comment                  Null String
  Prepared                 .F. (False)
  CompareMemo              .T. (True)
  FetchAsNeeded            .F. (False)

  View Field Properties    Default Value
  -------------------------------------

  KeyField                 .T. (True if the field is a Primary Key)
                           .F. (False if the field is not a Primary Key)
  Updatable                .F. (False)
  UpdateName               Database Container, Table Name And Field Name
  DataType                 Same as source field
  Caption                  Null String
  RuleExpression           Null String
  RuleText                 Null String
  Default                  Null String

The following View Properties are not available in Visual FoxPro 3.0 or Visual
FoxPro 3.0b:

  Prepared
  CompareMemo
  FetchAsNeeded

The following sample code creates a view based on the Customer table contained in
the \Samples\Data subdirectory of the Visual FoxPro installation folder. In
Visual FoxPro 6.0, Customer table is in the Microsoft Visual
Studio\Common\Samples\Data folder.

1. Create a program called Makeview.prg using the following code:

        thisversion=VERSION()
        IF LEFT(ALLTRIM(thisversion),6)="Visual"
          thisversion=VAL(SUBSTR(thisversion,15,2))
        ELSE
          thisversion=0
        ENDIF
        SET EXCLUSIVE ON
        SET MULTILOCKS ON
        OPEN DATABASE home()+"\SAMPLES\DATA\TESTDATA"
        CREATE SQL VIEW customerview ;
         AS SELECT DISTINCT cust_id, company, contact ;
        FROM testdata!customer ;
        ORDER BY customer.cust_id
        * Set view properties.
        =DBSETPROP('CUSTOMERVIEW','View','SendUpdates',.T.)
        =DBSETPROP('CUSTOMERVIEW','View','UpdateType',2)
        =DBSETPROP('CUSTOMERVIEW','View','WhereType',1)
        =DBSETPROP('CUSTOMERVIEW','View','BatchUpdateCount',3)
        =DBSETPROP('CUSTOMERVIEW','View','UseMemoSize',255)
        =DBSETPROP('CUSTOMERVIEW','View','FetchSize',100)
        =DBSETPROP('CUSTOMERVIEW','View','FetchMemo',.T.)
        =DBSETPROP('CUSTOMERVIEW','View','MaxRecords',10)
        =DBSETPROP('CUSTOMERVIEW','View','Tables','CUSTOMER')
        =DBSETPROP('CUSTOMERVIEW','View','Comment',"Demonstration View")
        IF thisversion>=5
        =DBSETPROP('CUSTOMERVIEW','View','Prepared',.F.)
        =DBSETPROP('CUSTOMERVIEW','View','CompareMemo',.T.)
        =DBSETPROP('CUSTOMERVIEW','View','FetchAsNeeded',.T.)
        ENDIF
        SELECT customer
        USE
        * Set Key and Updatable fields.
        =DBSETPROP('CUSTOMERVIEW.Cust_id','Field','KeyField',.T.)
        =DBSETPROP('CUSTOMERVIEW.Cust_id','Field','Updatable',.T.)
        =DBSETPROP('CUSTOMERVIEW.Cust_id','Field','UpdateName', ;
        'CUSTOMER.Cust_id')
        =DBSETPROP('CUSTOMERVIEW.Cust_id','Field','DataType',"C(12)")
        =DBSETPROP('CUSTOMERVIEW.Cust_id','Field','Caption','Primary Key')
        =DBSETPROP('CUSTOMERVIEW.Company','Field','KeyField',.F.)
        =DBSETPROP('CUSTOMERVIEW.Company','Field','Updatable',.T.)
        =DBSETPROP('CUSTOMERVIEW.Company','Field','UpdateName', ;
        'CUSTOMER.Company')
        =DBSETPROP('CUSTOMERVIEW.Company','Field','DataType',"N(15,2)")
        =DBSETPROP('CUSTOMERVIEW.Company','Field','Caption','Company Name')
        =DBSETPROP('CUSTOMERVIEW.Contact','Field','KeyField',.F.)
        =DBSETPROP('CUSTOMERVIEW.Contact','Field','Updatable',.F.)
        =DBSETPROP('CUSTOMERVIEW.Contact','Field','UpdateName', ;
        'CUSTOMER.Contact')
        =DBSETPROP('CUSTOMERVIEW.Contact','Field','DataType',"N(15,2)")
        =DBSETPROP('CUSTOMERVIEW.Contact','Field','Caption','Contact Name')
        USE customerview
        BROWSE
        RETURN

2. From the Command window, type:

        DO Makeview.prg

  The program creates an updateable view based on the Customer table.

Additional query words:

======================================================================
Keywords          : kbcode kbnokeyword kbHWMAC kbvfp300 kbvfp500 kbvfp600 
Technology        : kbHWMAC kbOSMAC kbVFPsearch kbAudDeveloper kbVFP300bMac kbVFP300 kbVFP300b kbVFP500 kbVFP600 kbVFP500a
Issue type        : kbhowto

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

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.