ONLINE HELP
 WINDEVWEBDEV AND WINDEV MOBILE

Help / WLanguage / Managing databases / HFSQL / HFSQL functions
  • Read operation according to a key
  • Checking the password
  • Miscellaneous
  • Comparing .ReadLast and <Source>.Last
  • Locks
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
Sets the position on the last record of a data file according to a browse item. The record is not read.
The number of the current Record is changed only when it is returned by the <Source>.RecNum function. For the functions handling by default the number of the current Record (functions <Source>.Delete, <Source>.Read, <Source>.Modify, ...), the value of this number is not updated: you must use <Source>.RecNum(). For example: not to do:
Client.Supprime()
but
Client.Supprime(Client.NumEnr())
get is from the smallest to the largest value of the path heading (see notes for 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, <Source>.Last sets the position in the data file to browse through the records that correspond to a condition. <Source>.Next is used to position on the next record corresponding to the condition.
Several cases may occur after the call to <Source>.Last:
  • a record corresponding to the condition was found: <Source>.Found returns True
  • the data file is empty or there is no record corresponding to the condition: <Source>.Out returns True
Remarks:

The highest value in the browse item is read (for more details, see remarks).
Caution: The record loaded in memory is not modified. HFSQL variables (e. g. Customer.Name, or the Name item of the Customer data file) are not updated.
In most cases, <Source>.Last is used to set the position in the data file in order to perform a read loop with <Source>.Previous.
Several cases may occur after the call to <Source>.Last:
  • the data file is empty or no record corresponds to the filter (defined by <Source>.Filter): <Source>.Out returns True.
  • the function tries to lock a record that is already locked in read-only: HErrorLock returns True and <Source>.Out returns True.

    Android Management of locks not available in SQLite databases.
Example
// Parcours d'un fichier de données depuis le dernier enregistrement
Client.Dernier(Nom)
TANTQUE PAS Client.EnDehors()
// Traitement de l'enregistrement
Client.Précédent(Nom)
FIN
Syntax
<Result> = <Source>.Last([<Search key item> [, <Options>]])
<Result>: Boolean
  • True if the position was set,
  • False if an error occurred. This problem can be caused by:
<Source>: Type corresponding to the specified source
Name of the data file used.
<Search key item>: Optional character string
Name of key item used to browse the data file. If this name is not specified, <Source>.Last will use the last browse item used on this data 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 set on the record selected by <Source>.Last:
hLockWriteLock in write mode: the selected record can be read by another application but it cannot be modified by another application.
hKeepFilterThe filter set by <Source>.Filter will be taken into account, even if the search key is not optimized for the filter. Reminder: <Source>.Filter returns the search key optimized for the filter.
Caution: in this case, performance issues may arise for large files.
hLockReadWriteLock in read/write: the selected record cannot be read or modified by another application.
hLockNoNo lock: the record can be read or modified by another application.
hNoRefresh
Native Connectors (Native Accesses) The table or query content will not be refreshed. All the saved positions are stored.
If this parameter is not specified, <Source>.Last reinitializes the browse for the specified item: the content of table or query is refreshed with the data found in the OLE DB database. All the saved positions are lost. The position will be restored according to the value of best item.
Remark: The browses and the positions saved on the other items are not affected.

Native 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.
AndroidAndroid Widget Management of locks not available in SQLite databases.
Remarks

Read operation according to a key

<Source>.Last 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.
If duplicates are found, <Source>.Last sets the position on the first "duplicate" record according to the sequence of record numbers.
Universal Windows 10 AppiPhone/iPadHFSQLHFSQL Client/Server

Checking the password

If <Source>.Last is the first function that handles the specified data file, the password is checked when opening the data file.
If the password is incorrect, HErrorPassword returns True and <Source>.Out returns True.

Miscellaneous

Comparing <Source>.ReadLast and <Source>.Last

<Source>.Last does not read the record: therefore, <Source>.Last is faster than <Source>.ReadLast.
iPhone/iPadHFSQLHFSQL Client/ServerNative 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.
Component: wd270hf.dll
Minimum version required
  • Version 25
This page is also available for…
Comments
Click [Add] to post a comment

Last update: 07/06/2023

Send a report | Local help