- Modifying the type of lock for a record
- Effect of lock mode
- Lock failure
- Number of locks
- Native SQL Server Connector: Lock in write mode
- Managing locks in OLE DB
- Persistence of lock
HLockRecNum (Function) In french: HBloqueNumEnr
  Not available with these kinds of connection
Locks a record and restricts the access to this record for all the other applications. Then, the record can be unlocked by HUnlockRecNum. Remark: Several cases may occur after the call to HLockRecNum: - The record is already locked by another application: the lock cannot be performed.
- The data file containing the record is entirely locked: the lock cannot be performed.
An automatic management of lock errors and modification conflicts is performed by default (except in the code of stored procedures). This assisted management of errors can be customized or disabled at any time by HOnError. Caution: HLockRecNum must be used with great care: when locked, the record is not read again. Therefore, it may have been deleted or modified since the last access to this record. It is recommended to use HRead with a lock option.
// Lock a record in the Customer data file
HLockRecNum(Customer, hCurrentRecNum, hLockReadWrite)
// Process on the record
...
// Restore access to the record
HUnlockRecNum()
Syntax
<Result> = HLockRecNum([<Data file> [, <Record to lock>]] [, <Lock>])
<Result>: Boolean - True if the operation was performed,
- False if a problem occurs. HError is used to identify the error.
<Data file>: Optional character string Name of the data file used.
If this name is not specified, HLockRecNum will use the last data file used by the last HFSQL function (function starting with "H"). <Record to lock>: Optional integer Number of the record to lock.
If this parameter is not specified, HLockRecNum will handle the current record. <Lock>: Optional integer constant Used to define the type of lock set on the record. | | | hLockNo | No lock: the record can be read or modified by another application. | | hLockReadWrite | Lock in read/write: the record in the data file cannot be read or modified by another application.
The other application will not be able to lock the record or the data file. | hLockWrite
(default value) | Lock in write mode: the record in the data file can be read, but cannot be modified by another application.
The other application will not be able to lock the record or the data file. |
Remarks Modifying the type of lock for a record To modify the type of record lock, call HLockRecNum and specify the requested type of lock. There is no need to unlock the record beforehand. Effect of lock mode If the data file lock mode is set to hModeMono (see HMode), HLockRecNum has no effect. Lock failure If the record is already locked, the lock request is retried HNbRetry times (50 by default). If the data file cannot be locked after H.NbRetry attempts, HErrorLock returns True. The H.Level variable indicates whether the record or the data file is locked. Number of locks The number of records that can be individually locked in a data file is unlimited.
This page is also available for…
|
|
|
|