In a BEFORE MODIFY or AFTER MODIFY trigger, be sure that you
    specify only the names of fields whose data values are to be
    changed, to avoid potentially unnecessary actions such as:

    o  Overlaying the data with itself within a record.

    o  Writing to the database (even though none of the fields in the
       record has actually changed values)

    o  Evaluating constraints that apply to fields in the MODIFY
       field list which have not changed values

    o  Evaluating MODIFY triggers that apply to fields in the MODIFY
       field list that have not changed values.

    o  Evaluating RDO VALID IF clauses for fields in the MODIFY field
       list that have not changed values.

    If there is a possibility that any of the fields in a MODIFY
    field list will not actually be changed, the triggered actions
    for any pertinent MODIFY triggers should be changed accordingly.

    For those cases in which a triggered action performs an operation
    based on the changed value for a particular field, the action
    should include a conditional expression that prevents execution
    of the operation if no value change occurs. The conditional
    expression, which compares the old value with the new value,
    should appear as part of the triggered action's WITH clause.