Hierarchical structure in PostgreSQL table

Question

I have a PostgreSQL table that contains the following structure:

Parent     child1     child2
1          10         12
2          13         
3

I want to have:

 Parent     child1     child2
    1          10         12
    2          13         13
    3          3          3

I mean, if child2 is NULL, I want to duplicate child1 into child2; and if child1 is null, I want to duplicate the parent into child1 and child2.

Colin 't Hart · Accepted Answer · 2013-09-25 09:19:28Z

1

Do you mean something like:

select Parent,
       coalesce(child1, Parent) as child1,
       coalesce(child2, child1, Parent) as child2
from <tablename>;

?

answered Sep 25, 2013 at 9:19

Colin 't Hart

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1 Comment

Yeeees, it's exactly what i was looking fooor. Thank you so muchhh for your quick answers.