The RDbDatabase class provides a member function, Execute(),
which directly executes both DDL and DML statements on the database.
As most of these statements can take an extended time to complete, there are also interfaces to execute these statements incrementally.
RDbIncremental provides
a member function, Execute(), which executes a DDL statement
incrementally.
RDbUpdate provides
the functionality for executing a DML statement incrementally.
DML statements need a different interface because it is not always possible to know how many steps a DML operation is going to need.