I think the /* END_REFRESH */ option provides the answer:
Refreshing derived fieldsWhen a record is refreshed, by default only the fields belonging to the updating table will be fetched from the database. Derived fields that result from joins, function calls, calculations, and so on will therefore not be refreshed. If you want to refresh derived fields as well, enable the roAllFields option.
This is accomplished by re-executing the SQL statement for just the current record. This requires that the where clause is extended with the rowid of the current record. Let's assume the following SQL statement:
select emp.*, dept.dname, dept.loc
from emp, dept
where dept.deptno = emp.deptnoBefore editing or after inserting or updating a record, the following statement will be executed to refresh all fields:
select emp.*, dept.dname, dept.loc
from emp, dept
where dept.deptno = emp.deptno
and emp.rowid = :doa__rowidIf however the statement is a little bit more complicated, problems can occur:
select emp.*, dept.dname, dept.loc
from emp, dept
where dept.deptno = emp.deptno
and emp.sal < 5000If a record is inserted or updated that does not meet the criteria, it would not be fetched anymore. Let's assume you update a record and set the 'sal' field to 6000. The following statement would no longer retrieve a record because emp.sal < 5000 is no longer true:
select emp.*, dept.dname, dept.loc
from emp, dept
where dept.deptno = emp.deptno
and emp.sal < 5000
and emp.rowid = :doa__rowidTo prevent this problem, you can add an /* END_REFRESH */ hint in the SQL statement that tells the dataset which part of the where clause to exclude from the refresh statement:
select emp.*, dept.dname, dept.loc
from emp, dept
where dept.deptno = emp.deptno
/* END_REFRESH */
and emp.sal < 5000Note that the hint must be literally /* END_REFRESH */, and may not differ in any way.
