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Q133357: Differences Between Temporary and Permanent Relationships

Article: Q133357
Product(s): Microsoft FoxPro
Version(s): WINDOWS:3.0
Operating System(s): 
Keyword(s): 
Last Modified: 15-FEB-2000

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, version 3.0 
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SUMMARY
=======

Relationships between tables can be established to link the tables together
based on matching values in a field common to all the tables. The relationships
can be created to exist from one FoxPro session to another (permanent or
persistent) or temporarily for each time a table is used. Each type relationship
is created differently and exists or behaves, in Visual FoxPro, differently.

Generally, both types of relationships are used regularly in Visual FoxPro
programming.

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

Permanent or Persistent Relationships
-------------------------------------

Permanent or persistent relationships can only exist between tables stored in a
database container (as opposed to free tables). The relationship itself is
stored within the database container and therefore can exist from one Visual
FoxPro session to another until the relationship is explicitly terminated.

Persistent relationship can be created in the Database Designer using the table
indexes (as opposed to using the table fields).

Because persistent relationships are stored in the database container certain
functions can use these relationships as default links. Each time the tables
involved in the persistent relationship are used in the Query, View, or Data
Environment Designers, these persistent relationships are used as the default
links. Persistent relationships are used to store referential-integrity
information.

Temporary Relationships
-----------------------

Temporary relationships can exist between free tables or tables stored in a
database container. However, temporary relationships cannot be created between a
free table and a table in database container.

To create temporary relationships, use the SET RELATION TO command or create them
visually in the View window. They must be recreated each time the table is
used.

Another major difference between a Persistent and Temporary relationship is that
the Temporary relationship causes the record pointer in the child table to move
automatically when the parent record pointer moves.

REFERENCES
==========

Additional information regarding the definition, creation and removal of
Persistent and Temporary relationships can be found in the Visual FoxPro Help
menu and in the Visual FoxPro User's and Developer's Guides: Visual FoxPro
User's Guide, Page 67; Developer's Guide, Pages 131, 183.

Additional query words: VFoxWin

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Keywords          :  
Technology        : kbVFPsearch kbAudDeveloper kbVFP300
Version           : WINDOWS:3.0

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