Hi Dev,
The easy way to find out Resource ETC is , go to a project in CA PPM and team tab and you will see ETC based on resources, do a trace and you will be able to see the query. If you need at assignment level then go to the task tab and then to assignments, here you can get assignment level ETC for particular project.
Once get the query for one project then you can change the where clause to accommodate all the projects/task/team etc.
Hope this helps
Regards
Suman Pramanik