Cursors

Connecting to Firebird from ApplicationsFirebird Events

Cursors

In the current Firebird ODBC/JDBC driver, the Dynamic and Keyset cursors are modified to use the Static cursor, through which it is not possible to update sets.

For best performance, use the cursor ForwardOnly.

The read operators SQLFetch, SQLExtendedFetch and SQLScrollFetch use SQL_ROWSET_SIZE and SQL_ATTR_ROW_ARRAY_SIZE.

For best performance using BLOB fields, use the operator SQLBindParameter, regardless of the size of the BLOB field, as this will work much faster than using SQLPutData/SQLGetData.

To use the Firebird driver’s cursors, call the following statements:

// Specify that the Firebird ODBC Cursor is always used, then connect.
SQLSetConnectAttr( hdbc, SQL_ATTR_ODBC_CURSORS, (SQLPOINTER)SQL_CUR_USE_DRIVER, 0 );
SQLConnect( hdbc, (UCHAR*)connectString, SQL_NTS, NULL, 0, NULL, 0 );

ODBC Cursor Library

This topic is well documented in MSDN.However, we must stress the absolute requirement to use these statements before connecting:

// Specify that the ODBC Cursor Library is always used, then connect.
SQLSetConnectAttr( hdbc, SQL_ATTR_ODBC_CURSORS, (SQLPOINTER)SQL_CUR_USE_ODBC, 0 );
SQLConnect( hdbc, (UCHAR*)connectString, SQL_NTS, NULL, 0, NULL, 0 );

That data sets keys (?) in the rowset buffers.Updating the buffers requires this statement:

SQLFetchScroll( hstmtSel, SQL_FETCH_RELATIVE, 0 );