<Source>.Delete (Function)

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Handling a deleted record
Number of deleted records
Deleting a record from a query
Version of data file
Size of the data file
Deletion and lock
xBase/FoxFro

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WINDEV Mobile

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See also

<Source>.Delete (Function)

In french: <Source>.Supprime

Not available with this kind of connection

Deletes a record from a data file (query or view). The record is deleted logically and physically. It cannot be restored (unlike the records crossed by <Source>.Cross).

The following operations are performed:

the record is deleted: the record is rendered inactive and is no longer referenced in the index. The data is not kept.
the indexes (corresponding to the record keys) are deleted from the index file.
the memos associated with the record are deleted from the memo file.

After running <Source>.Delete, the record is inserted in the list of deleted records and will be reused by <Source>.Add.

The deleted record is no longer visible in the iteration on the current item. This record will no longer be visible in iterations on other items if these iterations are reinitialized.

WINDEV, WINDEV Mobile and WEBDEV offer automatic error handling for the following 5 types of error: Duplicate error, Integrity error, Password error, Modification conflict and status error during modification conflict, Blocking error. For more details, see HFSQL error handling help.

Note To delete all records in a data file, use <Source>.DeleteAll.

Example

// Supprime l'enregistrement numéro 123 
Client.Supprime(123)

// Suppression des commandes d'un client 
Commande.LitRecherchePremier(NumCli, ValNumCli)
WHILE Commande.Trouve() = True
	Commande.Supprime()
	Commande.LitSuivant()
END

// Suppression des commandes d'un client 
FOR EACH Commande where NumCli = ValNumCli
	Commande.Supprime()
END

Syntax

<Result> = <Source>.Delete([<Record number> [, <Options>]])

<Result>: Boolean

True if the record was deleted,
False if a problem occurred (locked record, etc. (see the special cases)). HErrorInfo is used to identify the error.
If the record to delete is already deleted, <Source>.Delete returns True.

<Source>: Type corresponding to the specified source

Name of HFSQL data file or view used.

<Record number>: Optional integer

Number of the record to delete. If this parameter is not specified (if it is equal to 0 or to the hCurrentRecNum constant), the current record will be deleted. However, the current record will remain the deleted record.

CAUTION: Do not confuse the Record number with the automation identifier associated with the Record.
In most cases, these two numbers are not identical. The record number is returned by <Source>.RecNum.
This parameter must correspond to the current record number (hCurrentRecNum constant).
JDBC access: This parameter must correspond to the current record number (constant hNumEnrEnCours).

<Options>: Optional constant

Configures the integrity management performed on the deleted record.
hIgnoreIntegrity Ignores the integrity check for this operation, even if the automatic integrity check is enabled (<Connection variable>.SetIntegrity)
This parameter is ignored.
Access through JDBC: This parameter is ignored.

Remarks

Handling a deleted record

A deleted record will not be read:
- nor by path functions: <Source>.First, <Source>.Last, <Source>.Next, <Source>.Previous, <Source>.ReadFirst, <Source>.ReadLast, <Source>.ReadNext, <Source>.ReadPrevious, <Source>.Forward, <Source>.Backward.
- or search functions: <Source>.SeekFirst, <Source>.ReadSeekFirst, <Source>.SeekLast, <Source>.ReadSeekLast.
A deleted record can be read by <Source>.Read. Its content will be incomplete or inconsistent.
The physical location of a deleted record can be immediately re-used by <Source>.Add for example.

Number of deleted records

<Source>.NbRec is used to find out the number of records deleted from the data file.

Note For compatibility with Hyper File 5.5, it is also possible to find out the number of records deleted using the H.NbSup variable.

Deleting a record from a query

Deleting a record from a query can be performed:

in the query result
in the data files handled by the query (hModifyFile constant used in <Source>.ExecuteQuery or <Source>.ExecuteSQLQuery). In this case, the hWithFilter constant is automatically selected.

Regardless of how the query is executed (with or without the constant hWithFilterconstant), the <Source>.Delete function can only be used on single-file requests.

Caution:

On non-HFSQL data files, there is no need to specify the constant hModifiesFile in functions <Source>.ExecuteQuery or <Source>.ExecuteSQLQuery: data files contributing to the query are automatically modified when the query result is modified.
Records cannot be deleted from a query that uses groups or aggregates.
Integrity and duplicates are not managed by operations on multi-file queries: it is advisable to use transactions to avoid any problems.

For more details, see Modifying the query content.

Version of data file

If <Source>.Delete is successful, the data file version number is modified. This version number is returned by <Source>.Version.

Size of the data file

The deletion of one or more records has no incidence on the total file size on disk. The locations left empty in the data files by the deletions will be re-used during the next additions of records (<Source>.Add). This feature is used to get better performance, the reduction of file size being costly in time.

However, if after many deletions it is necessary to reduce the size of a data file, it can be reindexed (via <Source>.Index, WDMap or the HFSQL Control Center).

Deletion and lock

If a lock problem occurs when "deleting" a record (attempt to delete a record locked in write mode for example), the record is not deleted and HErrorLock returns True.

xBase/FoxFro

The function <Source>.Delete function has the same effect as <Source>.Cross: the record is scratched, not deleted. Therefore, the record can be re-enabled using <Source>.Modify. In this case, <Source>.State returns the hStateCrossed constant for a deleted record (instead of hStateDel).

To physically delete the crossed records, you must use <Source>.Index.

FoxPro files The <Source>.Index function is not available

Component: wd300hf.dll