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Help / WLanguage / Managing databases / HFSQL / HFSQL functions
  • Read operation based on a key
  • Comparison between HNext and HReadNext
  • Miscellaneous
  • Locks
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Stored procedures
Sets the position on the next data file record according to a browse item. The record is not read.
The number of the current record is modified only when it is returned by HRecNum. For functions handling the current record number by default (functions HDelete, HRead, HModify, ...), the value of this number is not updated: you must use the HRecNum() function. For example: do not:
HDelete(Customer)
but
HDelete(Customer, HRecNum())

Values in the browse item are read in ascending order (for more details, see the remarks).
Warning: Recording loaded into memory is not modified. The HFSQL variables (for example Customer.Name, i.e. the Name item of the Customer file) are not updated.
Generally, HNext sets the position in the data file during a loop operation.
Several cases may occur after the call to HNext:
  • the data file is empty or there is no record corresponding to the filter (defined by function HFilter): function HOut returns True
  • the function attempts to block a record already blocked in playback: function HErrorLock returns True and function HOut returns True.
    Java JDBC access: Lock management is not available for databases accessed via JDBC.
Example
HFirst(Customer, Name)
WHILE HOut(Customer) = False
	// Process the record
	HNext(Customer, Name)
END
Syntax
<Result> = HNext([<Data file> [, <Search key item>] [, <Options>]])
<Result>: Boolean
  • True if the position was set,
  • False if an error occurs. This problem can be caused by:
    • or a positioning problem (empty data file, etc.): function HFound returns Faux and function HError returns 0.
    • an error: HError returns an integer other than 0. HErrorInfo returns more details.
<Data file>: Optional character string
Name of the HFSQL data file. If this parameter is an empty string (""), HNext manipulates the last data file used by the last HFSQL function (function starting with "H").
<Search key item>: Optional character string
Name of the key item used to loop through the data file. If this name is not specified, HNext 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 and the management of duplicates performed on the record selected by HNext:
hDistinctIf there are any duplicates, sets the position on a single record of the duplicates. This parameter is taken into account only if the iteration is performed on a key item.
By default, all duplicates are iterated over.
OLE DBNative Connectors (Native Accesses) This constant is ignored.
hLockNoNo blocking: the recording can be played back or modified by another application.
hLockReadWriteLock in read/write mode: the selected record cannot be read or modified by another application.
OLE DB Lock in write mode only: the record currently being read can be read by another application, but cannot be modified by another application..
Operating mode equivalent to the one of hLockWrite.
hLockWriteLock in write mode: the selected record can be read by another application, but cannot be modified by another application.
Java Access through JDBC: This parameter is ignored.
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 with HReadFirst will remain effective when HReadPrevious and HReadNext are called.
To change the lock mode, use:
Hyper File 5.5 The lock options are ignored. Use the lock functions (HLockRecNum) kept for backward compatibility.
Remarks

Read operation based on a key

HNext positions on the next record with the greatest key value. The sort order taken into account is the one specified in the analysis for this key.

Comparison between HNext and HReadNext

The function HNext function does not play the recording: the HNext is therefore faster than function HReadNext.

Miscellaneous

  • HRecNum returns the current record number.
  • HChangeKey changes the search key while keeping the position on the current record.
WINDEVJavaUser code (UMC)External languageHFSQL ClassicHFSQL 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.
Component: wd300hf.dll
Minimum version required
  • Version 9
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Last update: 12/07/2024

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