- Handling a crossed record
- Number of crossed records
- Version of data file
- Crossing a record from a query
- Special cases
- xBase files
In french: HRaye
Available only with these kinds of connection
Crosses a record in a data file. The record is deleted logically and it can be retrieved if necessary.
The following operations are performed:
- the record becomes inactive. The data is stored (which is not the case when a record is deleted by HDelete).
- the indexes (corresponding to the record keys) are deleted from the index file.
- the memos associated with the record are stored.
This function can be used on the data files, the HFSQL Mobile views or the queries.
// Crosses the record #123
// Cross the customer orders
HReadSeekFirst(ORDERS, CUSTNUM, ValCustNum)
WHILE HFound() = True
<Result> = HCross([<Data file> [, <Record number> [, <Options>]]])
- True if the record was crossed,
- False if an error occurred (locked record, integrity error, ...). HErrorInfo returns more details.
<Data file>: Optional character string
Name of HFSQL data file, query or view used.
If this parameter is an empty string (""), HCross manipulates the last data file used by the last HFSQL function (function starting with "H").
<Record number>: Optional integer
Number of the record to cross.
If this parameter is not specified (equal to 0 or to the hCurrentRecNum constant), the current record will be crossed.
<Options>: Optional constant
- the lock mode applied to the crossed record. If no lock constant is specified, the crossed record is not locked.
|No lock: the crossed record will not be locked.|
|hLockReadWrite||Lock in read/write: the current crossed record cannot be read or re-enabled by another application.|
|hLockWrite||Lock in write mode: another application can read and consult the current crossed record (HRead) but cannot re-enable it. Only the current application can re-enable it.|
- the integrity management applied to the crossed record.
|hCheckIntegrity||Checks the integrity for the operation, even if the automatic integrity check is disabled (HSetIntegrity).|
|hIgnoreIntegrity||Ignores the integrity check for this operation, even if the automatic integrity check is enabled (HSetIntegrity).|
A WLanguage error occurs if the two constants are used at the same time. These constants have no effect on the cascading deletion.
Handling a crossed record
- A crossed record will not be read:
- by iteration functions: HFirst, HLast, HNext, HPrevious, HReadFirst, HReadLast, HReadNext, HReadPrevious, HForward, HBackward
- by the search functions: HSeekFirst, HReadSeekFirst, HSeekLast, HReadSeekLast.
- A crossed record can be read by HRead.
- A crossed record can be re-enabled by HModify or HWrite.
- HState is used to find out the record status (active, crossed, deleted, etc.).
- The physical location of a crossed record can only be reused (by HAdd for example) after:
- the execution of HFree,
- a reindex operation (with compression).
Number of crossed records
is used to find out the number of crossed records in the data file.
Remark: For backward compatibility with WEBDEV 1.5/WINDEV 5.5, the number of crossed records can also be returned by the H.NbDel variable.
Version of data file
is successful, the data file version number is modified. This version number is returned by HVersion
Crossing a record from a query
A record can be crossed:
- in the query result.
- in the files handled by the query (hModifyFile constant used in HExecuteQuery or HExecuteSQLQuery). In this case, the hWithFilter constant is automatically selected.
Regardless of the query execution mode (with or without the hWithFilter constant), HCross can only be used on single-file queries.
- Records cannot be crossed in a query that uses groups or aggregates.
- The management of integrity and duplicates is not performed during the operations on the multi-file queries: it is recommended to use transactions to avoid any problems.
- Managing locks:
If a lock problem occurs when "crossing" a record (attempt to cross a record locked in write mode for example), the record is not modified and HErrorLock returns True.
- Managing the referential integrity
If the management of the referential integrity is enabled (HSetIntegrity) and if the integrity is not checked during the deletion, HCross is not run. HErrorIntegrity must be checked after HCross.
- Deleted records
HCross must not be called on a record that was deleted beforehand.
have the same effect: the record is crossed but it is not deleted. Therefore, the record can be re-enabled using HModify
. In this case, HState
returns the hStateCrossed
constant for a deleted record (instead of hStateDel
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