Terminating Transactions and Connections

TERMINATING TRANSACTIONS AND CONNECTIONS

The ODBC interface provides functions that terminate statements, transactions, and connections, and free statement (hstmt), connection (hdbc), and environment (henv) handles.

Terminating Statement Processing

To free resources associated with a statement handle, an application calls SQLFreeStmt. The SQLFreeStmt function has four options:

SQL_CLOSE Closes the cursor, if one exists, and discards pending results. The application can use the statement handle again later.

SQL_DROP Closes the cursor if one exists, discards pending results, and frees all resources associated with the statement handle.

SQL_UNBIND Frees all return buffers bound by SQLBindCol for the statement handle.

SQL_RESET_PARAMS Frees all parameter buffers requested by SQLBindParameter for the statement handle.

To cancel a statement that is executing asynchronously, an application:

Calls SQLCancel. When and if the statement is actually canceled is driver- and data source–dependent.

Calls the function that was executing the statement asynchronously. If the statement is still executing, the function returns SQL_STILL_EXECUTING; if it was successfully canceled, the function returns SQL_ERROR and SQLSTATE S1008 (Operation canceled); if it completed normal execution, the function returns any valid return code, such as SQL_SUCCESS or SQL_ERROR.

Calls SQLError if the function returned SQL_ERROR. If the driver successfully canceled the function, the SQLSTATE will be S1008 (Operation canceled).

Terminating Transactions

An application calls SQLTransact to commit or roll back the current transaction.

Terminating Connections

To terminate a connection to a driver and data source, an application performs the following steps:

1. Calls SQLDisconnect to close the connection. The application can then use the handle to reconnect to the same data source or to a different data source.

2. Calls SQLFreeConnect to free the connection handle and free all resources associated with the handle.

3. Calls SQLFreeEnv to free the environment handle and free all resources associated with the handle.