JetOpenTable Function

Artikkel
08/26/2021

Applies to: Windows | Windows Server

JetOpenTable Function

The JetOpenTable function opens a cursor on a previously created table.

    JET_ERR JET_API JetOpenTable(
      __in          JET_SESID sesid,
      __in          JET_DBID dbid,
      __in          const tchar* szTableName,
      __in_opt      const void* pvParameters,
      __in          unsigned long cbParameters,
      __in          JET_GRBIT grbit,
      __out         JET_TABLEID* ptableid
    );

Parameters

sesid

The database session context to use.

dbid

The database identifier to use to find the table.

szTableName

The name of the table to open.

pvParameters

Deprecated. Set to NULL.

cbParameters

Deprecated. Set to 0 (zero).

grbit

A group of bits specifying zero or more of the following options.

Value	Meaning
JET_bitTableDenyRead	The table cannot be opened for read-access by another database session.
JET_bitTableDenyWrite	The table cannot be opened for write-access by another database session.
JET_bitTableNoCache	Do not cache the pages for this table.
JET_bitTablePermitDDL	Allows DDL modification on tables flagged as FixedDDL. This option must be used with the JET_bitTableDenyRead option.
JET_bitTablePreread	Provides a hint that the table is probably not in the buffer cache, and that pre-reading may be beneficial to performance.
JET_bitTableReadOnly	Requests read-only access to the table.
JET_bitTableSequential	The table should be very aggressively prefetched from disk because the application will be scanning it sequentially.
JET_bitTableUpdatable	Requests write-access to the table.

ptableid

On success, points to the identifier of the table. On failure, the contents for ptableid are undefined.

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_errInvalidDatabaseId	dbid is not a valid database identifier.
JET_errInvalidgrbit	A bad combination of grbit was passed in.
JET_errInvalidName	The name given in szTableName is invalid. For more information about valid table names, see the szTableName parameter in JetCreateTable.
JET_errObjectNotFound	An attempt was made to open a table that does not exist in the database.
JET_errOutOfCursors	The operation failed because the engine cannot allocate the resources required to open a new cursor. See the Remarks section.
JET_errTableInUse	The table is being used by another database operation.
JET_wrnTableInUseBySystem	A nonfatal warning indicating that the table is being used by the system.
JET_errTableLocked	The table is locked by another database operation.
JET_errTooManyOpenTables	An attempt was made to open too many unique tables at once. See the Remarks section.

Remarks

Tables opened with JetOpenTable should usually be closed with JetCloseTable. The exception to this rule happens when JetOpenTable is called in a transaction and the transaction is rolled back (with JetRollback). When rolling back a transaction, the table is automatically closed. In this case, it is an error to close the table with JetCloseTable.

It is legal to open system tables with JetOpenTable (for example, MSysObjects, MSysUnicodeFixup). The schema of the system tables may change, so accessing system tables is discouraged. The number of unique tables that can be opened simultaneously is affected directly by JET_paramMaxOpenTables. If the table is currently open then a new cursor will be created on the table. Cursor resources are configured using JetSetSystemParameter with JET_paramMaxCursors. Also see JetDupCursor.

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.
Unicode	Implemented as JetOpenTableW (Unicode) and JetOpenTableA (ANSI).

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JetOpenTable Function