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
, ...), the value of this number is not updated: you must use HRecNum
(). For example: not to do:
The greatest value of the browse item is read (see remarks
for more details).
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, 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 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.
Note: From version 19, HFSQL is the new name of HyperFileSQL.
// Browse a data file from the last record
WHILE NOT HOut()
// Process the record
<Result> = HLast([<Data file>] [, <Search key item> [, <Options>]])
- 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 (""), HLast handles the last data file used by the last HFSQL management function (functions that start 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, 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 browse 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.
This constant cannot be used.
|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.|
The table or query content will not be refreshed. All the saved positions are stored.
If this parameter is not specified, HLast
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.
Note: The browses and the positions saved on the other items are not affected.
The lock options will have no effect if the locks are not supported by the OLE DB provider or by the Native Access.
The lock options are ignored. Use the lock functions (HLockRecNum
) kept for backward compatibility.
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
does not read the record: therefore, HLast
is faster than HReadLast
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 specified by HStartLock
, use the hLockNo