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- Read operation according to a key item or not
- Memos
- Looping through records that match a condition
- Modifying the value of search key
- Locks
- Miscellaneous
HReadNext (Function) In french: HLitSuivant
 Not available with this kind of connection
Sets the position on the next data file record according to a browse item. The record is read and the HFSQL variables are updated (Customer.Name for example, which means the Name item of Customer file). Values in the browse item are read in ascending order (for more details, see the remarks). HReadNext is used to position in the data file during a browse loop. This function can only be run: Several cases may occur after the call to HReadNext:
- the file is empty or no record exists 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 locks are not available in PHP.
 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.
HReadFirst(Customer, Name)
WHILE HOut() = False
HReadNext(Customer, Name)
END
Syntax
<Result> = HReadNext([<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 the data file, view or query used. If this parameter is an empty string (""), HReadNext 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, view or query. If this name is not specified, HReadNext will use:- In the case of a data file: the last browse item used on this data 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 ORDER BY of the query if it exists, otherwise according to the last field used.
- In the case of a view In the case of a view: the sort item of the view (if it exists), otherwise on the last item used.
<Options>: Optional constant (or combination of constants) Used to configure:- the lock set on the record read by HReadNext
- the management of duplicates. By default, all duplicates are iterated over.
| | | hDistinct | If duplicates are found, this constant allows you to read a single record among the duplicates. This parameter is taken into account only if the iteration is performed on a key item.
| | 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. |
Remarks Read operation according to a key item or not If the item is a key, HReadNext reads the record with the greatest key value. The sort order taken into account is the one specified in the analysis for this key. Note In the case of a search loop (e.g. function HReadSeekFirst), when function HReadNext reads the record for which the key value is greatest, function HFound lets you know whether the record matches the search criterion or not. If the item is not a key, HReadNext reads the next 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). Looping through records that match a condition In most cases, HReadSeek, HReadSeekFirst and HReadSeekLast are used to position in the data file to perform a browse loop among the records corresponding to a condition. HReadNext and HReadPrevious are used to read the next or previous record corresponding to the condition: - if the item used is a key, HReadNext will read the next records corresponding to the values greater than or equal to the sought value.
- if the item used is not a key, HReadNext will read the next records corresponding to the values equal to the sought value.
To ignore the search while going to the next or previous record, use one of the following functions: Modifying the value of search key If the value of the browse item is modified before HReadNext is used, the current record can be read again by HReadNext in the rest of the browse. Changing the browse item updates the file index key. This modification is taken into account when reading the next records. This remark is also valid when using HReadNext without search key a sorted query (ORDER BY). 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.
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