JetDelete Function

Artikkel
08/26/2021

Applies to: Windows | Windows Server

JetDelete Function

The JetDelete function deletes the current record in a database table.

    JET_ERR JET_API JetDelete(
      __in          JET_SESID sesid,
      __in          JET_TABLEID tableid
    );

Parameters

sesid

The database session context that will be used for the API call.

tableid

The cursor on a database table. The current row will be deleted.

Return Value

This function returns the JET_ERR datatype with one of the following return codes. For more information about the possible ESE errors, see Extensible Storage Engine Errors and Error Handling Parameters.

Return code	Description
JET_errSuccess	The operation completed successfully.
JET_errCallbackFailed	The callback function failed in some manner. For example, access violations in callback functions are caught and translated into JET_errCallbackFailed. This error will only be returned by Windows XP and later.
JET_errClientRequestToStopJetService	It is not possible to complete the operation because all activity on the instance associated with the session has ceased as a result of a call to JetStopService.
JET_errIllegalOperation	The cursor specified by tableid does not support deletion. See the Remarks section.
JET_errInstanceUnavailable	It is not possible to complete the operation because the instance associated with the session has encountered a fatal error that requires that access to all data be revoked to protect the integrity of that data. This error will only be returned by Windows XP and later releases.
JET_errNoCurrentRecord	The cursor specified by tableid is not on a record.
JET_errNotInitialized	It is not possible to complete the operation because the instance associated with the session has not been initialized yet.
JET_errRestoreInProgress	It is not possible to complete the operation because a restore operation is in progress on the instance associated with the session.
JET_errPermissionDenied	The database engine does not have sufficient permissions to delete the record. This may happen if the database file was opened with read-only access.
JET_errRollbackError	An update buffer (see JetPrepareUpdate) exists, but not all of the changes made to columns of type JET_coltypLongText and/or columns of type JET_coltypLongBinary could be rolled back.
JET_errSessionSharingViolation	It is illegal to use the same session from more than one thread at the same time. This error will only be returned by Windows XP and later releases.
JET_errTermInProgress	It is not possible to complete the operation because the instance associated with the session is being shut down.
JET_errTransReadOnly	The transaction is a read-only transaction, and does not support deletes.
JET_errVersionStoreOutOfMemory	The operation failed because there is not enough memory to retain transactional information about the update.
JET_errWriteConflict	Another session has previously locked the record for update. The update attempted by this session will fail.

On success, the currency is left just before the next record. If the deleted record was the last in the table, the currency is left at the end of the table (that is, after the new last record). If the deleted record was the only record in the table, the currency is set to the beginning.

The appropriate indexes are automatically updated.

If an update is prepared (using JetPrepareUpdate), it will be canceled. The update buffer will be reset.

On failure, the currency remains unchanged. If an update is prepared (see JetPrepareUpdate), the update buffer may be reset.

Remarks

Not all tables support deletion of rows. A temporary table does not normally support deletion of rows. Deletion of records may be enabled on temporary tables for many reasons, some of which are:

JET_bitTTUpdatable was specified during creation.
Large temporary tables can support deletion if they were created with JET_bitTTScrollable or JET_bitTTIndexed. The threshold at which a temporary table becomes "large" is currently 64 kilobytes, but it may be changed in future releases.

Windows XP and later. Callback functions can be invoked by JetDelete, including JET_cbtypBeforeDelete and JET_cbtypAfterDelete.

It is important to understand the impact of performing a large number of update operations inside of a single transaction. Each update to the database must be tracked by the database engine in the version store. The version store holds a live record of all the different versions of each record or index entry in the database that can be seen by all active transactions. These versions are used to support the multi-versioned concurrency control in use by the database engine to support transactions using snapshot isolation. Once the database engine has exhausted the resources used to store these versions then it can no longer accept further changes until some transactions have concluded to allow these resources to be reclaimed. When the engine is in this state, all updates will fail with JET_errVersionStoreOutOfMemory. The resources available to the database engine to store these versions can be controlled using JetSetSystemParameter with JET_paramMaxVerPages and JET_paramGlobalMinVerPages.

Requirements

Requirement	Value
Client	Requires Windows Vista, Windows XP or Windows 2000 Professional.
Server	Requires Windows Server 2008, Windows Server 2003, or Windows 2000 Server.
Header	Declared in Esent.h.
Library	Use ESENT.lib.
DLL	Requires ESENT.dll.

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JetDelete Function