Q130659: PRB: "The database must be opened exclusively" Multiuser Error

Article: Q130659
Product(s): Microsoft FoxPro
Version(s): 3.0
Operating System(s): 
Keyword(s): kbnetwork kbprogramming
Last Modified: 12-AUG-1999

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

- Microsoft Visual FoxPro for Windows, versions 3.0, 5.0, 5.0a 
-------------------------------------------------------------------------------

SYMPTOMS
========

In a multiuser situation, when you perform tasks that affect the contents of a
database (.DBC file), the error "The database must be opened exclusively" is
displayed.

CAUSE
=====

The command requires exclusive access to the database. Several commands that
create or modify database objects require that the database not be shared--at
design time or run time.

This error may also occur at run time in an application or EXE if you have
included the database(s) in the project. By including the database(s) in the
project, you have caused them to be read-only, and you will not be able to
properly validate the database. In this situation, it is possible for ISE
CLUSIVE() to return a .T. (true) value and still get the error message described
above.

WORKAROUND
==========

If you receive the error "The database must be opened exclusively" at design
time, all developers must close the database before you can proceed.

To prevent this error from occurring at run time when manipulating views or
connections, create a local database for each user. All users will have
exclusive access to their database, and will also be able to update the table
records contained in a centralized, shared database.

To verify whether or not a database is open exclusively, use the ISEXCLUSIVE()
function. The syntax for the ISEXCLUSIVE() function is:

  ISEXCLUSIVE([cTableAlias | nWorkArea | cDatabaseName [, nType]])

When the nType parameter has a value of 2, the function returns the exclusive
status for a database. The following example code makes sure the database is
open exclusively before using the INDEX ON command:

     CLOSE ALL
     OPEN DATABASE SYS(2004)+"SAMPLES\DATA\TESTDATA"
     SELECT 0
     USE CUSTOMER
     IF ISEXCLUSIVE('testdata',2)
        INDEX ON CITY TAG CITY
        ELSE
        =MESSAGEBOX("Database must be opened Exclusively")
     ENDIF
     CLOSE DATABASE

NOTE: The above code uses CLOSE ALL to close all the files so that the database
can be opened but not selected, making the CLOSE DATABASE command useless. Of
course using CLOSE DATABASE ALL might not be helpful if only one database needs
to be closed. Therefore, issue the following code to select a certain database
to close and reopen:

     SET DATABASE TO <dbc name>
     CLOSE DATABASE
     OPEN DATABASE <dbc name> EXCLUSIVE

This ensures that the correct database container is selected, closed, and
reopened.


STATUS
======

This behavior is by design.

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

If a view or a table contained in a database is open for shared use, the
database is also shared. Therefore, all multiuser applications require that a
database be shared.

However, commands that directly relate to the database (.DBC file) structure and
commands that involve the creation or deletion of objects require exclusive use
of the database. These commands include:

  CREATE TABLE
  MODIFY STRUCTURE
  ALTER TABLE
  ADD TABLE
  RENAME TABLE

  CREATE SQL VIEW
  MODIFY VIEW
  DELETE VIEW
  RENAME VIEW

  CREATE CONNECTION
  MODIFY CONNECTION
  DELETE CONNECTION
  RENAME CONNECTION

  INDEX ON && You can however use INDEX ON on a view
  DELETE TAG

  CREATE TRIGGER
  DELETE TRIGGER

  APPEND PROCEDURES
  COPY PROCEDURES
  MODIFY PROCEDURE

  COMPILE DATABASE
  PACK DATABASE
  VALIDATE DATABASE

Additional query words: denied

======================================================================
Keywords          : kbnetwork kbprogramming 
Technology        : kbVFPsearch kbAudDeveloper kbVFP300 kbVFP500 kbVFP500a
Version           : 3.0
Issue type        : kbprb

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

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.

Copyright Microsoft Corporation 1986-2002.