Ask for a sql sentence(procedure) for copy data to themselves' table

Question

two tables
order and orderitem,there are relationship table;
order's id is PK
orderitem's id is PK,and parentId is FK.
and all id are created by sequences:order_id_seq and orderitem_id_seq.
order
id name
1 aaa
2 bbb
orderitem
id parentId num
1 1 100
2 1 150
3 2 200
4 2 300
now I want to copy these data to themselves table.how to code the sql or the procedure??the main problem i encoutered is how to update the parentId of the orderitem table?
Message was edited by:
user577067
Message was edited by:
user577067

Answer 1

now i want to copy order table's data to order,and copy data of orderitem table to orderitem.and after that the table data should be
order
id name
1 aaa
2 bbb
3 aaa
4 bbb
orderitem
id parentId num
1 1 100
2 1 150
3 2 200
4 2 300
5 3 100
6 3 150
7 4 200
8 4 300
Message was edited by:
user577067