Transaction processing in DB2 ODBC

Transaction processing is the second core task after initialization. During this task, SQL statements query and modify data in DB2® ODBC.

The following figure shows the typical order of function calls in a DB2 ODBC application. It does not show all functions or possible paths.

The transaction processing task contains five general steps:

Allocating statement handles
Preparing and executing SQL statements
Processing results
Committing or rolling back
Optionally, freeing statement handles if the statement is unlikely to be executed again

Statement handle allocation
A statement handle refers to the data object that describes and tracks the execution of an SQL statement. You must allocate a statement handle before you can execute a statement.
Preparation and execution of SQL statements
After you allocate a statement handle, you can specify and execute SQL statements.
How an ODBC program processes results
After an application executes an SQL statement, it must process the results that the statement produced. The type of processing that an application performs depends on the type of SQL statement that it initially issues.
Commit and rollback in DB2 ODBC
DB2 ODBC supports two commit modes: autocommit and manual-commit. A transaction is a recoverable unit of work or a group of SQL statements that can be treated as one atomic operation. This means that all the operations within the group are guaranteed to be completed (committed) or undone (rolled back), as if they were a single operation.
Function for freeing statement handles
You call the SQLFreeHandle() function (with HandleType set to SQL_HANDLE_STMT) to terminate processing for a particular statement handle.

Parent topic: Conceptual view of a DB2 ODBC application