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Functions.RLock Method (Usual)

Lock the current record.

Namespace:  XSharp.RT
Assembly:  XSharp.RT (in XSharp.RT.dll) Version: 2.18
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Type: Usual
Specifies the work area name or number for a table on which the operation must be performed.

Return Value

Type: Logic
TRUE if the record lock(s) is (are) obtained; otherwise, FALSE.
If you try to lock more than one record and one of them fails then locks that were successful are released again.
An attempt to lock a record in an empty database returns TRUE.
If a database file is opened in shared mode, you must obtain a record lock before attempting any operation that writes to the database file. For each invocation of RLock(), there is one attempt to lock the target record, and the result is returned as a logical value.
An attempt to obtain a record lock fails if another process currently has a file lock or record lock on the target record. If RLock() is successful, the record is locked and other processes are prevented from updating the record until the lock is released. RLock() provides a shared lock, allowing other users read-only access to the locked record while allowing only the current process to modify it. A record lock remains in effect until you explicitly unlock it (with DBUnLock(), for example), close the database file, or attempt another file or record lock (with RLock() or DBRLock() without an argument). By default, this function operates on the currently selected work area. It can be made to operate on an unselected work area by specifying it within an aliased expression or by calling the overload that accepts a workarea parameter (a workarea number or alias ). This feature is useful since RLock() does not automatically attempt a record lock for related files.
This example deletes a record in a shared database file using RLock():
 1USE customer INDEX custname SHARED NEW
 2SEEK "Smith"
 3IF Customer->Found()
 4    IF Customer->RLock()
 5        Customer->DBDelete()
 6        QOut("Smith deleted")
 7    ELSE
 8        QOut("Record in use by another")
 9    ENDIF
11    QOut("Smith not in Customer file")
See Also