Re: Self Join Help

Thanks for you help thus far.
The final goal would be to achieve results like ->
parent | child
------------+------------
Foo |
Apache | PHP
XHTML |
News | Tech News
News | World News

Im playing with the SQL to see if its possible, but any insight would be
appreciated.
Thanks again.

apz wrote:

> this is second time I post to a forum, and second time I correct
> myself... ugh, I should delay posting by 15 minutes, or stop
> re-reading my emails after posting... ;D
>
> anyways:
>
> apz wrote:
>
>> test=# select a.topicname as parent, b.topicname as child from topics
>> as a left join topics as b on a.id = b.pid;
>>
>> parent | child
>> --------+------------
>> XHTML | null
>> Foo | null
>> Apache | PHP
>> News | Tech News
>> News | World News
>
>
> this actually should return:
>
>
> test=# select a.topicname as parent, b.topicname as child from topics as
> a left join topics as b on a.id = b.pid;
>
> parent | child
> ------------+------------
> XHTML | null
> Foo | null
> Apache | PHP
> News | Tech News
> News | World News
> PHP | null
> Tech News | null
> World News | null
>
>
> the querry with left join should return child=null if a node is a leaf.
> so XHTML and PHP return child as null because neither have any nodes
> underneath.
> this also should mean that topicname should not allow null values, not
> to confuse ourselves further on.
>
> so two ways are:
> - add one node which is always root, use your querry
> - use left join, when no child then child returns as null
>
>
>
> /apz, You can always tell luck from ability by its duration.
>
>
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