Tree with multiple root nodes does not display

Question

I am trying to create a tree to display some hierarchical data which contains several root nodes.
I have specifed that the TREE_ROOT value is always Null as the root nodes have a null value for the PARENT_ID. The page displays yet none of the data is displayed.
I have manage to get it to work by creating a dummy single root that I reference from the existing root values?

Answer 1

Phattam,
The TREE_ROOT identifies the root node's ID, not its PARENT_ID.
For example, if we build a tree on the oehr_employees table, the ID is EMPLOYEE_ID and the PARENT_ID is MANAGER_ID. therefore, to identify the start of the tree, we could populate the TREE_ROOT with a select statement e.g.
SELECT employee_id FROM oehr_employees WHERE employee_id = 100This identifies a single value and the tree starts from employee_id 100.
If we used a select statement that retrieves more than one row, e.g.
SELECT employee_id FROM oehr_employees WHERE manager_id = 100then the tree starts at one of the children of employee_id 100 - ApEx will not show a tree that has more than one starting node. If you want to show these alternative starting points, you'll need to do exactly what you have done - create a 'dummy' root node.
Hope this helps,
Bryan.