A recursive query is supported in Oracle 9i. When you use itself in your table, you can build a tree structure with a SQL statement, which is very convenient!
Such as:
Table Department
ID parent_id name
1 0 ### Company
2 1 Market Department
3 1 Technical Department
4 3 R & D Department
5 3 Network
6 3 After-sales Service Department
7 1 Finance Department
Simply use the SQL query to construct a tree structure
Select Department.id, RPAD ('', Level * 3-2, ') ||' '|| Department.name from Department Start with Parent_Id =' 0 'Connect by Prior Department.oid = Department.parent_ID
The results of the query are as follows:
1 | - ### Company
2 | - Marketing Department
3 | - Technical Department
4 | - R & D department
5 | - Network Department
6 | - After-sales service department
7 | - Finance Department
It is very convenient to recurrent query sub-nodes in its own relational table, and the condition can be recursively query the parent node.
