Executes a statement or group of statements once for each record
    in a record stream formed by a record selection expression (RSE).
    Oracle Rdb evaluates all variables when the RSE is compiled, not
    when the statements within the FOR loop execute. For detailed
    information on the RSE, request HELP on RSE.

    Example:

    RDO>   FOR E IN EMPLOYEES WITH E.EMPLOYEE_ID = "00164"
    cont>    MODIFY E USING E.MIDDLE_INITIAL = "M"
    cont>    END_MODIFY
    cont>  END_FOR