Recursive joins / how to define query using connect by clause

Question

Hi,
I have a table A have 1-1 reltionship with table Employee
Structure of table is as follows
Table A
id name employee_id
100 aa 1
200 bb 2
300 cc 3
400 dd 4
500 ee 5
Table Employee
id parent_id
1 null
2 1
3 2
4 3
5 1
6 1
I want to get all records from A table whose employee_id is equal to 2 or (recursive)decendants/child of employee with id 2 (i.e. employee with id 2,3,4 )
i.e I want recursively join where in I get records from table A as
id name employee_id
200 bb 2
300 cc 3 (because it is child of employee with id 2)
400 dd 4 (becaue it is child of employee with id 3 which is child of 2)
I know we can use In clause , but it will be performance wise not good.
Can we do it in Toplink without using IN clause?
Oracle has connect by clause, but other database might not have this caluse. So how can write a toplink query which can run on any database.
Any help is highly appreciated.
Thanks a lot.

Answer 1

You can use TopLink's Hierarchical Query support but this only works with Oracle DB as it relies on the database to perform the query.
--Shaun