Cursor Behaviors
ODBC supports the ISO options for specifying the behavior of cursors by specifying their scrollability and sensitivity. These behaviors are specified by setting the SQL_ATTR_CURSOR_SCROLLABLE and SQL_ATTR_CURSOR_SENSITIVITY options on a call to SQLSetStmtAttr. The SQL Server Native Client ODBC driver implements these options by requesting server cursors with the following characteristics.
Cursor behavior settings |
Server cursor characteristics requested |
|---|---|
SQL_SCROLLABLE and SQL_SENSITIVE |
Keyset-driven cursor and version-based optimistic concurrency |
SQL_SCROLLABLE and SQL_INSENSITIVE |
Static cursor and read-only concurrency |
SQL_SCROLLABLE and SQL_UNSPECIFIED |
Static cursor and read-only concurrency |
SQL_NONSCROLLABLE and SQL_SENSITIVE |
Forward-only cursor and version-based optimistic concurrency |
SQL_NONSCROLLABLE and SQL_INSENSITIVE |
Default result set (forward-only, read-only) |
SQL_NONSCROLLABLE and SQL_UNSPECIFIED |
Default result set (forward-only, read-only) |
Version-based optimistic concurrency requires a timestamp column in the underlying table. If version-based optimistic concurrency control is requested on a table that does not have a timestamp column, the server uses values-based optimistic concurrency.
Scrollability
When SQL_ATTR_CURSOR_SCROLLABLE is set to SQL_SCROLLABLE, the cursor supports all the different values for the FetchOrientation parameter of SQLFetchScroll. When SQL_ATTR_CURSOR_SCROLLABLE is set to SQL_NONSCROLLABLE, the cursor only supports a FetchOrientation value of SQL_FETCH_NEXT.
Sensitivity
When SQL_ATTR_CURSOR_SENSITIVITY is set to SQL_SENSITIVE, the cursor reflects data modifications made by the current user or committed by other users. When SQL_ATTR_CURSOR_SENSITIVITY is set to SQL_INSENSITIVE, the cursor does not reflect data modifications.