Positions on the last file record according to a search 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:
but
HDelete(Customer, HRecNum())
The reading is performed for the greatest value of search 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,
HLast is used to position in the data file in order to perform a read loop with
HPrevious.
Several cases may occur after the call to HLast:
- 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.
The management of locks is performed on the HFSQL Client/Server data files and on the data files handled by Native Access. A HFSQL Mobile record cannot be locked. Indeed, the operating system of Pocket PC does not allow you to lock records.
Access by JDBC: The management of locks is not available for the databases accessed by JDBC.
The management of locks is not available for the SQLite databases.
Versions 15 and later
New in version 15Versions 17 and later New in version 17 Versions 18 and later New in version 18 Versions 21 and later New in version 21 Note: From version 19, HFSQL is the new name of HyperFileSQL.
// Browse a file from the last record
HLast(Customer, Name)
WHILE NOT HOut()
// Process the record
HPrevious(Customer, Name)
END
Syntax
<Result> = HLast([<File Name> [, <Name of 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.
<File Name>: Optional character string (with or without quotes)
Name of data file used. If this parameter corresponds to an empty string (""), HLast handles the last data file used by the last function for HFSQL management (starting with the letter H).
<Name of 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, HLast 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 search item is automatically used.
<Options>: Optional constant
Configures the lock performed on the record selected by HLast: | |
| hLockWrite | Lock in write mode: the selected record can be read by another application but it cannot be modified by another application.
|
| hKeepFilter | The 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, poor performance may occur on huge data files.
|
| hLockReadWrite | Lock in read/write: the selected record cannot be read or modified by another application. |
| hLockNo | No lock (even if HStartLock was called): the record can be read or modified by another application. |
| hNoRefresh | |
Remarks
Read operation according to a key
HLast positions 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, HLast positions on the last "duplicate" record according to the sequence of record numbers.
- The current record number is returned by HRecNum.
- HChangeKey is used to modify the search key while being positioned on the current record.
Comparing HReadLast and HLast
HLast does not read the record: therefore,
HLast is faster than
HReadLast.