Using Cursors
ODBC supports a cursor model that allows:
- Several types of cursors.
- Scrolling and positioning within a cursor.
- Several concurrency options.
- Positioned updates.
ODBC applications rarely declare and open cursors or use any cursor-related Transact-SQL statements. ODBC automatically opens a cursor for every result set returned from an SQL statement. The characteristics of the cursors are controlled by statement attributes set with SQLSetStmtAttr before the SQL statement is executed. The ODBC API functions for processing result sets support the full range of cursor functionality, including fetching, scrolling, and positioned updates.
This is a comparison of how Transact-SQL scripts and ODBC applications work with cursors.
| Action | Transact-SQL | ODBC |
|---|---|---|
| Define cursor behavior | Specify through DECLARE CURSOR parameters | Set cursor attributes by using SQLSetStmtAttr |
| Open a cursor | DECLARE CURSOR OPEN cursor_name |
SQLExecDirect or SQLExecute |
| Fetch rows | FETCH | SQLFetch or SQLFetchScroll |
| Positioned update | WHERE CURRENT OF clause on UPDATE or DELETE | SQLSetPos |
| Close a cursor | CLOSE cursor_name DEALLOCATE |
SQLCloseCursor |
The server cursors implemented in Microsoft® SQL Server™ support the functionality of the ODBC cursor model. The SQL Server ODBC driver uses server cursors to support the cursor functionality of the ODBC API.