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  • Read operation according to a key
  • Checking the password
  • Various
  • Comparison between HReadFirst and HFirst
  • Locks
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Stored procedures
Sets the position on the first record of a data file according to the specified 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, HFirst 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 HFirst:
  • 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, HFirst is used to perform a generic search.
Remark: From version 19, HFSQL is the new name of HyperFileSQL.

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 set the 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 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.

Remark: From version 19, HFSQL is the new name of HyperFileSQL.
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 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 data file used. If this parameter corresponds to an empty string (""), HFirst will use the last data file used by the last HFSQL management function (function starting with "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 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 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.
OLE DB Lock in write mode: the selected record can be read by another application but it cannot be modified by another application. Equivalent to hLockWrite.

hKeepFilterThe filter set by HFilter will be taken into account, even if the search key is not optimized for the filter. Reminder: HFilter returns the optimized search key for the filter.
Caution: In this case, performance issues may arise for large data files.
Hyper File 5.5 This variable cannot be used.
hNoRefresh
OLE DB The table or query content will not be refreshed. All the saved positions are stored. If this parameter is not specified, HFirst 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.
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 mode specified by HFirst will remain effective during the calls to HPrevious and HNext.
To modify the lock mode, you must use:
Native Connectors (Native Accesses) Oracle: 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

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 sets the position on the first "duplicate" record according to the sequence of record numbers.
WEBDEV - Server codeAjaxHFSQLHFSQL Client/ServerHyper File 5.5

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 remaining positioned on the current record.

Comparison between HReadFirst and HFirst

HFirst does not read the record: therefore, HFirst is faster than HReadFirst.
WEBDEV - Server codeAjaxHFSQLHFSQL Client/ServerHyper File 5.5OLE 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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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