Terminates a transaction and undoes all changes that have been
    made to the database since the program's most recent START_
    TRANSACTION statement. The ROLLBACK statement also closes all
    open streams and releases all locks. The ROLLBACK statement
    affects both data manipulation and data definition statements.

    Example:

    RDO> START_TRANSACTION READ_WRITE
    RDO> DEFINE FIELD LOCATION_CODE DATATYPE TEXT SIZE 5.
    RDO> ! Oops, wrong size!
    RDO> ROLLBACK
    RDO> START_TRANSACTION READ_WRITE
    RDO> DEFINE FIELD LOCATION_CODE DATATYPE TEXT SIZE 7.
    RDO> COMMIT

1  –  Format

  (B)0ROLLBACK qqwqqqqqqqqqqqqqqqqqqqqqqq>qqqqqqqqqqwqwqqqqqqqqqqqqqqqqwqqq>
             mq> (TRANSACTION_HANDLE qq> var) qqj mqq> on-error qqqj

1.1  –  TRANSACTION_HANDLE

    A keyword followed by a host language variable. A transaction
    handle identifies each instance of a transaction. If you do not
    declare the transaction handle explicitly, Oracle Rdb attaches an
    internal identifier to the transaction.

    In Callable RDO, use !VAL as a marker for host language
    variables.

    You can put parentheses around the host language variable name.

    Normally, you do not need to use this argument. The ability to
    declare a transaction handle is provided for compatibility with
    other database products and future releases of Oracle Rdb.

1.2  –  on-error

    The ON ERROR clause, which specifies a host language statement to
    be performed if an Oracle Rdb error occurs. For more details, request
    HELP on ON_ERROR.

2  –  More

    If you have invoked a database, you have the necessary privileges
    to use the ROLLBACK statement.

3  –  Example

    Roll back changes made during a transaction with a COBOL program:

    GET-ID-NUMBER.
          DISPLAY "Enter employee ID number:  "
             WITH NO ADVANCING.
          ACCEPT EMPLOYEE-ID.
    CHANGE-SALARY.
          DISPLAY "Enter new salary amount:  "
             WITH NO ADVANCING.
          ACCEPT SALARY-AMOUNT.

    &RDB&   START_TRANSACTION READ_WRITE
    &RDB&    FOR S IN SALARY_HISTORY WITH
    &RDB&       E.EMPLOYEE-ID = EMPLOYEE-ID
    &RDB&          MODIFY USING
    &RDB&             S.SALARY-AMOUNT = SALARY-AMOUNT
    &RDB&          END-MODIFY
    &RDB&   END-FOR

          DISPLAY EMPLOYEE-ID, SALARY-AMOUNT.
          DISPLAY "Is this figure correct? [Y or N]  "
             WITH NO ADVANCING.
          ACCEPT ANSWER.
          IF ANSWER = "Y" THEN
    &RDB&   COMMIT
          ELSE
    &RDB&   ROLLBACK
            DISPLAY "Please enter the new salary amount again."
            GO TO CHANGE-SALARY.