PC SOFT

ONLINE HELP
 WINDEVWEBDEV AND WINDEV MOBILE

Home | Sign in | English EN

  • Read operation according to a key item or not
  • Memos
  • Miscellaneous
  • Lock
WINDEV
WindowsLinuxUniversal Windows 10 AppJavaReports and QueriesUser code (UMC)
WEBDEV
WindowsLinuxPHPWEBDEV - Browser code
WINDEV Mobile
AndroidAndroid Widget iPhone/iPadIOS WidgetApple WatchMac CatalystUniversal Windows 10 App
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 <Source>.Backward:
  • no other record exists in the data file: function <Source>.Out 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 <Source>.Out returns True.
    PHP Management of locks not available in PHP.
    Java Access by JDBC: The management of locks is not available for 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 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
// Recule jusqu'au 200ème enregistrement du fichier de données Client
// selon la clé NomCli
Client.LitDernier(NomCli)
Client.Recule(NomCli, 199)
Syntax
<Result> = <Source>.Backward([<Item> [, <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.
<Source>: Type corresponding to the specified source
Name of data file, view or query used.
<Item>: Optional character string
Name of item according to which the browse is performed. If this name is not specified, function <Source>.Backward will handle the last of the data file field used by the last HFSQL maintenance function (function beginning with the letter H).
OLE DBNative Connectors (Native 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: 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.

    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.
  • 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: <Source>.ReadFirst, <Source>.First, <Source>.ReadSeekFirst, <Source>.SeekFirst, <Source>.ChangeKey, <Source>.ReturnPosition.
If the item used is a key item:
  • if the hDistinct constant is not enabled, <Source>.Backward moves backward of <Step> key values from the current position.
  • if the hDistinct constant is enabled, <Source>.Backward 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,
  • <Source>.Backward 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. The <Source>.SetMemo function allows you to customize this automatic reading.
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 (<Source>.ExtractMemo).

Miscellaneous

WINDEVWEBDEV - Server codeReports and QueriesUniversal Windows 10 AppiPhone/iPadJavaUser code (UMC)External languageAjaxHFSQLHFSQL Client/ServerHyper File 5.5OLE DBNative Connectors (Native 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.
Component: wd270hf.dll
Minimum version required
  • Version 25
This page is also available for…
Comments
Click [Add] to post a comment