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- Read operation according to a key item or not
- Locks
- Memos
- Password
- Miscellaneous
HReadLast (Function) In french: HLitDernier
Not available with this kind of connection
Sets the position on the last record of a data file according to a browse item. The record is read and the HFSQL variables are updated (e. g. Customer.Name, in other words, the Name item in the Customer data file). The highest value in the browse item is read (for more details, see remarks). In most cases, HReadLast is used to set the position in the data file in order to perform a read loop with HReadPrevious. Several cases may occur after the call to HReadLast: - the data file is empty or there is no record corresponding to the filter (defined by function HFilter): no read is performed and function HOut returns True.
- the function attempts to block a record already blocked for playback: no playback is performed, function HErrorLock returns True and function HOut returns True.
The management of locks is not available.
JDBC access: lock management is not supported for databases that are accessed through JDBC.
This function can be used with the data files, HFSQL views or queries.
HReadLast(Customer, Name)
WHILE HOut() = False
HReadPrevious(Customer, Name)
END
Syntax
<Result> = HReadLast([<Data file> [, <Browse item>] [, <Options>]])
<Result>: Boolean Corresponds to: - False if an error occurs. In this case, HError returns an integer other than 0. HErrorInfo returns more details about the error. The record is not read.
- the value of HFound in the other cases (the record can be read, even if <Result> returns False).
<Data file>: Optional character string Name of data file, HFSQL view or query used. If this parameter is an empty string (""), HReadLast manipulates the last data file used by the last HFSQL function (function starting with "H"). <Browse item>: Optional character string Name of item used to loop through the data file or the view. If this name is not specified, HReadLast will use:- In the case of a data file: the last browse item used on this file by the last HFSQL management function (function beginning with the letter H).. If this item does not exist, the best browse item is automatically used.
- In the case of a query: the ORDER BY of the query if it exists, otherwise the last field used.
- In the case of a view: the view's sort item (if it exists), otherwise the last item used.
<Options>: Optional constant (or combination of constants) Configures:- the lock set on the record read by HReadLast.
- whether the filter that was defined must be taken into account.
| | hForwardOnly | | hKeepFilter | The 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, on large data files, performance problems may occur..
| hLockNo | No blocking: the recording can be played back or modified by another application during playback..
| hLockReadWrite | Read/write lock: the record being read cannot be read or modified by another application.
| hLockWrite | Write lock: the record currently read can be read by another application but it cannot be modified by another application.
| hNoRefresh | |
Remarks Read operation according to a key item or not If the item is a key, HReadLast reads the record with the greatest key value. The sort order taken into account is the one specified in the analysis for this key. If duplicates are found, HReadLast reads the last "duplicate" record according to the sequence of record numbers.
If the item is not a key, HReadLast reads the last active record. When browsing the data file, the records will be sorted according to their record number. In this case, the selected browse item will appear in red in the code editor and a warning will be displayed in the "Code" pane. Memos The memos associated with the record can be automatically read (or not) when reading the record. HSetMemo is used to customize this automatic read operation. If the memos are supported, the associated text memos are read when the record is read. The binary memos are read only when they are explicitly used ( HExtractMemo). Miscellaneous - HRecNum returns the current record number.
- HChangeKey changes the search key while keeping the position on the current record.
- To optimize the first iterations on a data file, use HOptimize on this data file.
- This function replaces HReadLastLock and HReadLastNoLock, which were kept for compatibility with WINDEV 5.5.
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