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  • Read operation according to a key item or not
  • Memos
  • Various
  • Lock
WINDEV
WindowsLinuxUniversal Windows 10 AppJavaReports and QueriesUser code (UMC)
WEBDEV
WindowsLinuxPHPWEBDEV - Browser code
WINDEV Mobile
AndroidAndroid Widget iPhone/iPadApple WatchUniversal Windows 10 AppWindows Mobile
Others
Stored procedures
Moves backward several records from the current position in the data file, according to a specified item.
The destination record is read and loaded in memory: the HFSQL variables are updated (Customer.Name for example, which means the Name item of Customer file).
Several cases may occur after the call to HBackward:
  • no other record exists in the data file: HOut returns True. No read operation is performed.
  • the function tries to lock a record that is already locked in read-only: HErrorLock returns True and HOut returns True.
    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.
    PHP The management of locks is not available in PHP.
    Java Access by JDBC: The management of locks is not available for the databases accessed by JDBC.
This function can be used with the data files, HFSQL views or queries.
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.
Note: 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
// Moves backward to the 200th record of CUSTOMER file
// according to the CUSTNAME key
HReadLast(CUSTOMER, CUSTNAME)
HBackward(CUSTOMER, CUSTNAME, 199)
Syntax
<Result> = HBackward([<File Name> [, <Item Name>] [, <Step> [, <Options>]]])
<Result>: Boolean
  • True if the backward move was performed in the data file,
  • False if an error occurred (lock, end of file, etc.): the record is not read. HError is used to identify the error.
<File Name>: Optional character string (with or without quotes)
Name of data file, view or query used. If this name is not specified, HBackward handles the last data file used by the last function for HFSQL management (starting with the letter H).
<Item Name>: Optional character string (with or without quotes)
Name of item according to which the browse is performed. If this name is not specified, HBackward handles the last file item used by the last function for HFSQL management (starting with the letter H).
OLE DBNative Accesses All the items used to move backward in the file are considered as being key items.
PHP The <Step> parameter is mandatory if this parameter is not specified.
<Step>: Optional integer
Number of steps backward (which means number of records to browse). By default, <Step> = 1.
<Options>: Optional Integer constant (or combination of constants)
Configures:
  • the lock mode applied to the record read. By default, the lock performed corresponds to the current lock.
    hLockNoNo lock (even if HStartLock was called): the record can be read or modified by another application during the reading.
    hLockWriteLock in write mode: the record currently read can be read by another application but it cannot be modified by another application.
    hLockReadWriteLock in read/write: the record currently read cannot be read or modified by another application.

    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.
    OLE DBNative Accesses The lock options will have no effect if the locks are not supported by the OLE DB provider or by the Native Access.
  • the management of duplicates during the browse. By default, all the duplicates are browsed.
    hDistinctWhen a browse is performed on a key item, a single record is browsed if duplicates are found.
Hyper File 5.5 <Options> is ignored.
PHP <Options> is ignored.
Java Access by JDBC: <Options> is ignored.
Remarks

Read operation according to a key item or not

In all cases, the browse operation must have been initialized by one of the following functions: HReadFirst, HFirst, HReadSeekFirst, HSeekFirst, HChangeKey, HRestorePosition.
If the item used is a key item:
  • if the hDistinct constant is not enabled, HBackward moves backward of <Step> key values from the current position.
  • if the hDistinct constant is enabled, HBackward moves backward of <Step> distinct key values from the current position. If duplicates are found, a single duplicate is read.
If the item used is not a key item:
  • the hDistinct constant is not available,
  • HBackward moves backward of <Step> active records from the current position.

Memos

The memos associated with the record can be automatically read (or not) when reading the record. HSetMemo is used to customize this automatic read operation.
If the memos are supported, the associated text memos are read when the record is read. The binary memos are read only when they are explicitly used (HExtractMemo).

Various

WINDEVWEBDEV - Server codeReports and QueriesiPhone/iPadUniversal Windows 10 AppJavaAjaxUser code (UMC)External languageHFSQLHFSQL Client/ServerHyper File 5.5OLE DBNative Accesses

Lock

By default (no lock variable specified), the lock performed corresponds to the current lock mode.
If a lock is requested (hLockWrite or hLockReadWrite constant), the record will be read and locked only if this record is not already locked by another application.
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 performed by HStartLock, use the hLockNo constant.
Components
WINDEVWEBDEV - Server codeReports and Queries wd230hf.dll
Windows Mobile wp230hf.dll
Java wd230java.jar
Linux wd230hf.so
Android wd230android.jar
Minimum required version
  • Version 9
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