Re: [SQL] Trees in SQL (again)

>
> I'm trying to implement set model of trees in SQL and I found a problem:
>
> How to find first level children of parent?
>
> For this structure (with left and right set values):
>
>           1 Jerry 10
>               |
>      -------------------
>      |                 |
>  2 Bert 3          4 Chuck 9
>                        |
>                  ------------
>                  |          |
>              5 Donna 6  7 Fred 8
>
> The question is: Who is first level child of Jerry?
> The answer should produce:
>         Bert
>         Chuck

    The  children  must  know. It is the same situation as in the
    unix filesystem. And that's why there  is  a  '..'  entry  in
    every directory, pointing to the inode of the parent.

    So  each  node must have a field identifying it's parent. The
    root node (Jerry)  might  simply  point  back  to  itself  to
    identify that.


Jan

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