#include <db_cxx.h>
class DbTxn {
public:
    DB_TXN *DbTxn::get_DB_TXN();
    const DB_TXN *DbTxn::get_const_DB_TXN() const;
    static DbTxn *DbTxn::get_DbTxn(DB_TXN *txn);
    static const DbTxn *DbTxn::get_const_DbTxn(const DB_TXN *txn);
    ...
}; 
      
            The DbTxn object is the handle for a transaction. Methods of
            the DbTxn handle are used to configure, abort and commit the
            transaction. DbTxn handles are provided to 
            Db methods in order
            to transactionally protect those database operations.
        
            DbTxn handles are not free-threaded; transactions handles
            may be used by multiple threads, but only serially, that is, the application must
            serialize access to the DbTxn handle. Once the 
            DbTxn::abort() or 
            DbTxn::commit() methods are called, the handle
            may not be accessed again, regardless of the method's return. In addition, parent
            transactions may not issue any Berkeley DB operations while they have active child
            transactions (child transactions that have not yet been committed or aborted) except for
            DbEnv::txn_begin(), 
            DbTxn::abort() and 
            DbTxn::commit().
        
            Each DbTxn object has an associated
            DB_TXN struct, which is used by the underlying
            implementation of Berkeley DB and its 
            
            C++ language
            API. The DbTxn::get_DB_TXN() method
            returns a pointer to this struct. Given a const DbTxn object, 
            txnMget_const_DB_TXN()
            returns a const pointer to the same struct.
        
            Given a DB_TXN struct, the DbTxn::get_DbTxn()
            method returns the corresponding DbTxn object, if there is
            one. If the DB_TXN object was not associated with a
            DbTxn (that is, it was not returned from a call to
            DbTxn::get_DB_TXN()), then the result of
            DbTxn::get_DbTxn is undefined. Given a const
            DB_TXN struct, DbTxn::get_const_DbTxn()
            returns the associated const DbTxn object, if there is one.
        
These methods may be useful for Berkeley DB applications including both C and C++ language software. It should not be necessary to use these calls in a purely C++ application.