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  • Modifying the type of lock for a data file
  • Effect of lock mode
  • Lock failure
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Stored procedures
Locks a data file and restricts the access to this data file for all other sites or applications. Then, the data file can be unlocked by HUnlockFile.
Several cases may occur after the call to HLockFile:
  • A file record is already locked by another application: the lock cannot be performed.
  • The data file is already locked by another application: the lock cannot be performed.
HErrorLock returns True if a lock problem occurs.
AndroidAndroid Widget Windows Mobile This function can be used with HFSQL Client/Server data files.
Versions 17 and later
iPhone/iPad This function is now available for iPhone/iPad applications.
New in version 17
iPhone/iPad This function is now available for iPhone/iPad applications.
iPhone/iPad This function is now available for iPhone/iPad applications.
Versions 18 and later
Universal Windows 10 App This function is now available in Windows Store apps mode.
New in version 18
Universal Windows 10 App This function is now available in Windows Store apps mode.
Universal Windows 10 App This function is now available in Windows Store apps mode.
Remark: From version 19, HFSQL is the new name of HyperFileSQL.
Versions 19 and later
Android This function is now available for Android applications.
Android Widget This function is now available in Android Widget mode.
New in version 19
Android This function is now available for Android applications.
Android Widget This function is now available in Android Widget mode.
Android This function is now available for Android applications.
Android Widget This function is now available in Android Widget mode.
Versions 21 and later
Universal Windows 10 App This function is now available in Universal Windows 10 App mode.
New in version 21
Universal Windows 10 App This function is now available in Universal Windows 10 App mode.
Universal Windows 10 App This function is now available in Universal Windows 10 App mode.
Example
// Lock the CUSTOMER file
IF HLockFile(CUSTOMER, hLockReadWrite) = False THEN
IF HErrorLock() = True THEN
Error("Operation not allowed")
END
END
// Process on the file ...
...
// Give access back to the file
HUnlockFile()
Syntax
<Result> = HLockFile([<File name> [, <Lock>]])
<Result>: Boolean
  • True if the lock was performed,
  • False if a problem occurred (the file is already locked for example). HError is used to identify the error.
<File name>: Optional character string (with or without quotes)
Name of data file used. If this name is not specified, HLockFile handles the last data file used by the last function for HFSQL management (starting with the letter H).
<Lock>: Optional integer constant
Used to define the type of lock performed on the data file:
hLockWrite
(default value)
Lock in write mode: the records found in the data file can be read by another application but cannot be modified by another application. No lock on the data file can be defined by another application.
hLockReadWriteLock in read/write: the records found in the data file cannot be read or modified by another application. No lock on the data file can be defined by another application.
hLockNoNo effect

Windows Mobile The management of locks is performed on the HFSQL Client/Server data files and on the data files handled by native access. A HFSQL Mobile record cannot be locked. Indeed, the operating system of Pocket PC does not allow you to lock records.
AndroidAndroid Widget The management of locks is performed on the HFSQL Client/Server data files only.
Remarks

Modifying the type of lock for a data file

To modify the type of lock applied to a data file, call HLockFile and specify the requested type of lock. There is no need to unlock the data file beforehand.

Effect of lock mode

HLockFile has no effect if the lock mode of data file is set to hModeMono (see HMode).

Lock failure

If the data file (or one of its records) is already locked, the lock request is retried H.NbRetry times (50 by default).
If the data file cannot be unlocked after H.NbRetry attempts, HErrorLock returns True.
Component : wd250hf.dll
Minimum version required
  • Version 9
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