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Controls whether dBASE Plus opens tables and their associated index and memo files in exclusive or shared mode.
SET EXCLUSIVE on | OFF
When you issue SET EXCLUSIVE ON, subsequent tables you open—and their associated indexes and memos—are in exclusive mode, unless you open them with USE...SHARED. When you open a table in exclusive mode, other users can't open, view, or change the file or any of its associated index and memo files. If you try to open a table that another user has opened in exclusive mode, or if you try to open in exclusive mode a table that another user has opened, an error occurs.
Exclusive use of a table is different than a file lock that you would get with FLOCK( ). With a file lock, others may have the table open and can read data, although only one user may have a file lock at any time. With exclusive use, no one else can have the table open.
SET EXCLUSIVE OFF causes subsequent tables you open—and their associated indexes and memos—to be in shared mode, unless you open them with USE...EXCLUSIVE. If a table in shared mode is in a shared network directory, other users on the network with access to the directory can open, view, and change the file and any of its associated index and memo files.
If you use SET INDEX and the table is open in exclusive mode, dBASE Plus opens the index in exclusive mode. If the table is open in shared mode by way of an overriding USE...SHARED, dBASE Plus opens the index in the mode specified by USE.
An index created with INDEX is opened in exclusive mode, regardless of whether the table is opened in shared or exclusive mode and regardless of the SET EXCLUSIVE setting. After creating an index, you can open the index in shared mode with USE...INDEX...SHARED or by issuing SET EXCLUSIVE OFF followed by SET INDEX TO.
The following commands require the exclusive use of a table with either SET EXCLUSIVE ON or USE...EXCLUSIVE:
EXCLUSIVE is always OFF. When a method like packTable( ) requires exclusive access to a table, the method always attempts to open the table in exclusive mode. If the table is already open in another query, the method will fail.