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  • Read operation according to a key
  • Checking the password
  • Various
  • Comparing HReadFirst and HFirst
  • Locks
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Stored procedures
Positions on the first file record according to the specified search item. The record is not read. The number of the current record is only changed when it is returned by the HRecNum function. For functions that manipulate by default the number of the current record (functions 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 read operation is performed from the lowest to the greatest 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, HFirst is used to position in the data file in order to perform a read loop with HNext.
Several cases may occur after the call to HFirst:
  • the data file is empty or there is no record corresponding 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 The management of locks is only performed on HFSQL Client/Server data files or data files handled by a Native Access. An HFSQL Mobile record cannot be locked. Indeed, the operating system of Pocket PC does not allow you to lock records.
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
HFirst(Customer, Name)
WHILE HOut() = False
        // Process the record
        HNext(Customer, Name)
END
Syntax
<Result> = HFirst([<Data file> [, <Search key item>] [, <Options>]])
<Result>: Boolean
  • True if the positioning was performed,
  • 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 data file used. If this parameter corresponds to an empty string (""), HFirst 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, HFirst handles the last search item used on this data file by the last function for HFSQL management (starting with the letter H). If this item does not exist, the best browse item is automatically used.
<Options>: Optional constant
Configures the lock performed on the record selected by HFirst:
hLockNoNo lock (even if HStartLock was called): the record can be read or modified by another application.
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.

hKeepFilterThe filter implemented by HFilter will be taken into account, even if the search key is not optimized for the filter. Reminder: HFilter returns the search key optimized for the filter.
Caution: In this case, lack of performances may occur on huge data files.
hNoRefresh
Windows Mobile The management of locks is only performed on HFSQL Client/Server data files or data files handled by a Native Access. An HFSQL Mobile record cannot be locked. Indeed, the operating system of Pocket PC does not allow you to lock records.
Native Connectors (Native Accesses) The lock options will have no effect if the locks are not supported by the OLE DB provider or by Native Access.
Native Connectors (Native Accesses) Oracle: a different lock mode can be specified for each record. However, if a transaction was started by SQLTransaction before implementing the lock, the lock will only be released at the end of the transaction (SQLTransaction associated with SQLCommit or SQLRollback).
Remarks

Read operation according to a key

HFirst positions on the record with the smallest key value.
The sort order is the one that was specified in the analysis for this key.
If duplicates are found, HFirst positions on the first "duplicate" record according to the sequence of record numbers.
iPhone/iPadWindows MobileUniversal Windows 10 AppHFSQLHFSQL Client/Server

Checking the password

If HFirst 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 HOut returns True.

Various

  • The current record number is returned by HRecNum.
  • HChangeKey is used to modify the search key while being positioned on the current record.

Comparing HReadFirst and HFirst

HFirst does not read the record: therefore, HFirst is faster than HReadFirst.
WINDEV MobileiPhone/iPadUniversal Windows 10 AppHFSQLHFSQL Client/ServerNative Connectors (Native Accesses)

Locks

By default (<Options> not specified), no lock operation is performed on the record.
If a lock is requested (hLockWrite or hLockReadWrite constant), the positioning on the record will be performed only if this record 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 performed by HStartLock, use the hLockNo constant.
Component : wd250hf.dll
Minimum version required
  • Version 9
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Comments
HFILER E FILETOARRAY
O filetoarray se não tiver antes dele um hfilter coloca no array a tabela inteira e se colocar o hfilter, traz só o registro. exemplos:

//assim vai trazer só o registro atual
HFilter(RADFileA,RADFileA.IDRADFileA,gnID)
FileToArray(garr_RADFileA_Depois,RADFileA,RADFileA.IDRADFileA)

//vai trazer todos os registros
FileToArray(garr_RADFileA_Depois,RADFileA,RADFileA.IDRADFileA)

DICA:
Voce pode atribuir uma Classe de um arquivo a um array assim:

garr_RADFileA_Antes is array of CMRADFileA
garr_RADFileA_Depois is array of CMRADFileA
BOLLER
24 Feb. 2019