How to self JOIN recursively in SQL?

Question

I have a table:

Series
========
ID
SeriesName
ParentSeriesID

A series can be a \"root\" series, (ParentSeriesID is 0 or null) or it can ha

Answer 1

I just enhance the work of Thomas. If you need to get the depth of the hierarchy and getting the parentid here is the code.

This was almost the same with Thomas' work.

With Family As 
( 
    Select s.ID, s.ParentSeriesId, 0 as Depth
    From Series s
    Where ID = @ParentID <--- this was removed if you intend to get all hierarchy of the record. You can retain this if you want
  Union All 
     Select s2.ID, s2.ParentSeriesId < --- change to **Family.ParentID**, Depth + 1
     From Series s2
     Join Family 
         On Family.ID = s2.ParentSeriesId 
) 
 Select *
 From Family 

That's all. I know it's too late but I hope anyone who encounter this may help them. Thanks Thomas for the original code. :)