Challenging query: traverse a tree using SQL?

Hi, SQL experts,

does anyone know if traversing a tree can be done using sql? For example:

   nodeid parentnodeid level

       3               3          1
       4               3          2
       8               3          2
       2               4          3
       1               4          3
       9               8          3
       7               8          3
       6               2          4
      10               7          4

Tree structure:
                         3
                   4           8
                2     1      9   7
                6                10 

Question:
Given a node id=4, how can I get a list of child node ids including itself order by level?

               4
               1
               2
               6

Any help will be greatly appreciated.

Leslie

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Leslie Tseng
lesliet_at_writeme.com


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