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  • Read operation according to a key
  • Comparison between HPrevious and HReadPrevious
  • Various
  • Locks
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Stored procedures
Positions on the previous file record according to a browse item. The record is not read.
The number of the current record is modified when it is returned by HRecNum. For the functions that handle the current record number (HDelete, HRead, HModify, ...), the value of this number is not updated: you must use HRecNum(). For example: not to do:
HDelete(Customer)
but
HDelete(Customer, HRecNum())
The reading is performed from the lowest to the greatest value of the browse item (see the remarks for more details).
Caution: The record loaded in memory is not modified. The HFSQL variables (Customer.Name for example, which means the Name item of Customer file) are not updated.
In most cases, HPrevious sets the position in the data file to browse through the records that correspond to a condition. HNext is used to position on the next record corresponding to the condition.
Several cases may occur after the call to HPrevious:
  • a record corresponding to the condition was found: HFound returns True
  • the data file is empty or there is no record corresponding to the condition: HOut returns True
Remarks:
  • By default, HSeekFirst and HSeekLast are used to perform an exact-match search.
  • By default, HPrevious is used to perform a generic search.
Versions 15 and later
Android This function is now available for the Android applications.
New in version 15
Android This function is now available for the Android applications.
Android This function is now available for the Android applications.
Versions 17 and later
iPhone/iPad This function is now available for the iPhone/iPad applications.
New in version 17
iPhone/iPad This function is now available for the iPhone/iPad applications.
iPhone/iPad This function is now available for the iPhone/iPad applications.
Versions 18 and later
Android Widget This function is now available in Android Widget mode.
Universal Windows 10 App This function is now available in Windows Store apps mode.
New in version 18
Android Widget This function is now available in Android Widget mode.
Universal Windows 10 App This function is now available in Windows Store apps mode.
Android Widget This function is now available in Android Widget 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 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.

The read operation is performed from the greatest to the lowest value of the browse item (see remarks for more details).
Caution: The record loaded in memory is not modified. The HFSQL variables (Customer.Name for example, which means the Name item of Customer file) are not updated.
In most cases, HPrevious is used to position in the data file during a browse loop.
Several cases may occur after the call to HPrevious:
  • the data file is empty or no record corresponds to the filter (defined by HFilter): HOut returns True.
  • the function tries to lock a record that is already locked in read-only: HErrorLock returns True and HOut returns True.
    Windows Mobile Locks are managed only on HFSQL Client/Server data files or on data files handled by a Native Connector. An HFSQL Mobile record cannot be locked. Indeed, the operating system of Pocket PC does not allow you to lock records.
    Java Access by JDBC: The management of locks is not available for databases accessed by JDBC.
Versions 15 and later
Android This function is now available for Android applications.
New in version 15
Android This function is now available for Android applications.
Android This function is now available for Android applications.
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
Android Widget This function is now available in Android Widget mode.
Universal Windows 10 App This function is now available in Windows Store apps mode.
New in version 18
Android Widget This function is now available in Android Widget mode.
Universal Windows 10 App This function is now available in Windows Store apps mode.
Android Widget This function is now available in Android Widget 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 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
HLast(Customer, Name)
WHILE HOut() = False
        // Process the record
        HPrevious(Customer, Name)
END
Syntax
<Result> = HPrevious([<Data file> [, <Search key item>] [, <Options>]])
<Result>: Boolean
  • True if the position was set,
  • False if an error occurred. This problem can be caused by:
    • a positioning problem (empty data file, ...): HFound returns False and HError returns 0.
    • an error: HError returns an integer other than 0. HErrorInfo returns more details.
<Data file>: Optional character string (with or without quotes)
Name of HFSQL data file used. If this parameter corresponds to an empty string, HPrevious handles the last data file used by the last function for HFSQL management (starting with the letter H).
<Search key item>: Optional character string (with or without quotes)
Name of key item used to browse the data file. If this name is not specified, HPrevious will use the last browse item used on this file by the last HFSQL management function (function starting with "H"). If this item does not exist, the best browse item is automatically used.
<Options>: Optional constant
Configures the lock and the management of duplicates performed on the record selected by HPrevious:
hLockWriteLock in write mode: the selected record can be read by another application but it cannot be modified by another application.
hLockReadWriteLock in read/write: the selected record cannot be read or modified by another application.
hLockNoNo lock (even if HStartLock was called): the record can be read or modified by another application.
hDistinctIf duplicates are found, it is used to position on a single record among the duplicates. This parameter is taken into account only if the browse is performed on a key item.
By default, all the duplicates are browsed.
Windows Mobile Locks are managed only on HFSQL Client/Server data files or on data files handled by a Native Connector. An HFSQL Mobile record cannot be locked. Indeed, the operating system of Pocket PC does not allow you to lock records.
Java Access by JDBC: This parameter is ignored.
OLE DBNative Connectors (Native Accesses) The lock options will have no effect if the locks are not supported by the OLE DB provider or by the Native Connector.
OLE DB The lock options specified by HPrevious will be ignored. The lock mode specified by HFirst or HLast will remain effective during the calls to HPrevious and HNext.
To modify the lock mode, you must use:
Native Connectors (Native Accesses) For Native Oracle Connector, a different lock mode can be specified for each record. However, if a transaction was started by SQLTransaction before setting the lock, the lock will only be released at the end of the transaction (SQLTransaction associated with sqlCommit or sqlRollBack).
Hyper File 5.5 The lock options are ignored. Use the lock functions (HLockRecNum) kept for backward compatibility.
Remarks

Read operation according to a key

HPrevious sets the position on the record with the greatest key value.
The sort order is the one that was specified in the analysis for this key.

Comparison between HPrevious and HReadPrevious

HPrevious does not read the record: therefore, HPrevious is faster than HReadPrevious.
WINDEVWEBDEV - Server codeiPhone/iPadUniversal Windows 10 AppWindows MobileJavaAjaxUser code (UMC)External languageHFSQLHFSQL Client/ServerStored proceduresHyper File 5.5OLE DBNative Connectors (Native Accesses)

Various

The current record number is returned by HRecNum.
HChangeKey is used to modify the search key while remaining positioned on the current record.
WINDEVWEBDEV - Server codeReports and QueriesiPhone/iPadUniversal Windows 10 AppAjaxUser code (UMC)External languageHFSQLHFSQL Client/ServerStored proceduresOLE DBNative Connectors (Native Accesses)

Locks

By default (<Options> not specified), the record is not locked.
If a lock is requested (hLockWrite or hLockReadWrite constant), the position will be set on the record only if it is not already locked.
There is no need to specify a lock parameter if the data file is locked by HStartLock: the lock specified by HStartLock is automatically taken into account. To ignore the lock set by HStartLock, use the hLockNo constant.
Component : wd250hf.dll
Minimum version required
  • Version 9
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