This example makes a change to a relation and writes that change
    to the database:

           DISPLAY "Enter employee's ID number:  "   <-- 1
             WITH NO ADVANCING.
           ACCEPT ID.
           DISPLAY "Percentage increase:  "    <-------- 2
             WITH NO ADVANCING.
           ACCEPT PERC.
           CALL "SYS$GETTIM" USING TODAY
                             GIVING RETURN_VALUE.

    &RDB&  START_TRANSACTION READ_WRITE      <---------- 3
    &RDB&     RESERVING SALARY_HISTORY FOR
    &RDB&     PROTECTED WRITE

    &RDB&  FOR S IN SALARY_HISTORY
    &RDB&    WITH  S.EMPLOYEE_ID = ID  AND   <---------- 4
    &RDB&      S.SALARY_END MISSING
    &RDB&    MODIFY S USING                  <---------- 5
    &RDB&        ON ERROR
                    GO TO ERROR-PAR
    &RDB&        END_ERROR
    &RDB&    S.SALARY_END = TODAY
    &RDB&    END_MODIFY

    &RDB&    STORE NEW IN SALARY_HISTORY USING    <----- 6
    &RDB&        ON ERROR
                   GO TO ERROR-PAR
    &RDB&        END_ERROR
    &RDB&      NEW.EMPLOYEE_ID = S.EMPLOYEE_ID;
    &RDB&      NEW.SALARY_AMOUNT =
    &RDB&        ( S.SALARY_AMOUNT *
    &RDB&        ( 1 + ( PERC / 100 ) ) );
    &RDB&      NEW.SALARY_START = TODAY
    &RDB&    END_STORE

    &RDB&  END_FOR

    &RDB&  COMMIT              <------------------------ 7

    This program fragment gives a raise to an employee. To maintain a
    consistent database, it performs the following operations:

    1. Prompts for an employee identification number (ID).

    2. Prompts for a percentage increase, which is used to calculate
       INCREASE.

    3. Starts a read/write transaction. This statement uses the
       RESERVING clause to protect the SALARY_HISTORY record against
       conflicting updates, while allowing users access to all the
       other relations in the database.

    4. Establishes a record stream consisting of the current SALARY_
       HISTORY record for the specified employee.

    5. Uses MODIFY to change the current salary record, by changing
       its date from missing to the current date (TODAY).

    6. Uses STORE to create a new SALARY_HISTORY record. Although
       this statement executes within the record stream defined
       by the FOR loop, it must declare a new context variable to
       identify the new record. All the fields of the new record
       can be derived from fields of the old one, except the start
       date, which must be calculated from the current date. Oracle Rdb
       calculates NEW.SALARY_AMOUNT from the S.SALARY_AMOUNT, using
       the specified percentage increase (PERC).

    7. Uses COMMIT to make the changes permanent to the database.

    Note that each data manipulation statement provides an ON ERROR
    clause. If an error occurs at any point in the transaction,
    control transfers to another paragraph, which contains a ROLLBACK
    statement. Therefore, this set of operations is never partially
    completed.