I Have populated master detail block from Data based want to change some values in data block and save it as a new record in Both master and child tables.
To Populate used execute query Changed values as record Save by commit
But as i used execute query to populate existing data on commit it is trying to update already saved data in table. But i want to create new records in DB with new primary key
That won't work, as you noticed. Records you fetched are database records so - once you update their values and commit, you overwrite data.
If you want to insert new records, then
Alternatively, don't use data block but control block (the one that isn't based on a database table). Populate it, somehow (e.g. you could create a button which calls the procedure; it uses a loop and populates record-by-record). Modify values you want and create your own procedure which will insert new rows into the database table. As of the primary key, it depends on how you do it; if it is a database trigger which uses a sequence, it (the trigger) will do the job. Otherwise, you'll have to create a primary key yourself (during the insert process).
