Export (0) Print
Expand All

OLE DB Cursors (SQL Server Compact)

Microsoft SQL Server Compact 4.0 supports the base table, forward-only, and scrollable cursor types. When any one of these supported cursors is used, the client can have only one open row.

The base table cursor is the fastest of the supported cursors and the only cursor that interacts directly with the storage engine. This cursor supports updates, bookmarks, and indexes, and the Seek and SetRangemethods of IRowsetIndex. The base table cursor optionally supports delayed update mode by displaying the IRowsetUpdate interface when the client passes DBPROP_IRowsetUpdate as TRUE. This cursor has dynamic membership; both DBPROP_OTHERINSERT and DBPROP_OTHERUPDATEDELETE properties are TRUE.

Base table cursors can be opened only by using IOpenRowset::OpenRowset. Using a "SELECT * FROM table" yields a query processor cursor, forward-only or scrollable, and not a base table cursor. Only base table cursors support updates.

Although the forward-only read-only cursor is the fastest query processor cursor and the second fastest cursor overall, this cursor provides the least amount of functionality. It does not support bookmarks or updates.

The scrollable read-only cursor is the most functional query processor cursor. The result set of this cursor is cached. This provides fast cursor restarts but makes it more resource intensive, especially for queries with large result sets. Because the results are cached, changes to the underlying base tables for a query are not reflected in the query results unless the query is re-executed.

The following table shows the required property settings for each cursor type.

Property setting

Base table

Forward-only

Scrollable

DBPROP_BOOKMARKS

VARIANT_TRUE

VARIANT_FALSE

VARIANT_TRUE

DBPROP_OWNUPDATEDDELETE

VARIANT_TRUE

VARIANT_FALSE

VARIANT_FALSE

DBPROP_OWNINSERT

VARIANT_TRUE

VARIANT_FALSE

VARIANT_FALSE

DBPROP_OTHERUPDATEDELETE

VARIANT_TRUE

VARIANT_FALSE

VARIANT_FALSE

DBPROP_OTHERINSERT

VARIANT_TRUE

VARIANT_FALSE

VARIANT_FALSE

DBPROP_CANFETCHBACKWARDS

VARIANT_TRUE

VARIANT_FALSE

VARIANT_TRUE

DBPROP_QUICKRESTART

VARIANT_TRUE

VARIANT_FALSE

VARIANT_TRUE

Show:
© 2014 Microsoft