Set Exclusive, Set("Exclusive")
This command
determines whether the default mode for opening tables is
exclusive or shared access.
Usage
|
SET EXCLUSIVE ON | OFF
cIsItExclusive = SET( "EXCLUSIVE" )
|
Parameter
|
Value
|
Meaning
|
cIsItExclusive
|
"ON"
|
Unless otherwise specified, open tables exclusive.
|
"OFF"
|
Unless otherwise specified, open tables shared.
|
Opening a table for exclusive access makes it totally unavailable
to other users, even to other applications on the same machine or
other forms with private data sessions in the same application.
You can't even read the data for reporting or queries. So you
only want to do it when you have to—such as when you need to
perform maintenance that requires exclusive access. (For example,
you need exclusive access to rebuild indexes, change table
structures, and so on.)EXCLUSIVE can improve system performance
tremendously, and should be considered for single-user
applications running in a non-networked environment.EXCLUSIVE can
be set differently for each data session. By default, it's ON for
the global, default data session, and OFF for all private data
sessions. The current SET EXCLUSIVE setting is used for all kinds
of operations that open tables, including SELECT-SQL, CREATE,
INSERT INTO, and any other command that opens a table to do its
work. The only way to override the current setting is to open the
table with USE and add either the SHARED or EXCLUSIVE keyword.
SET EXCLUSIVE also affects opening databases with OPEN DATABASE
or MODIFY DATABASE. Again, you can override the default in the
OPEN DATABASE command.SET("EXCLUSIVE") tells you the current
setting.
Example
|
SET EXCLUSIVE ON
USE Employee
INDEX ON UPPER(Last_Name+First_Name) TAG Name
|
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Ted Roche, Doug Hennig, and Della Martin. Click for license
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