Re: How to inquiry a nest result?

Hello

2011/11/10 shuaixf <shuaixf(at)gmail(dot)com>:
> --*Test SQL*
> CREATE TABLE tb(id integer primary key,
>                name varchar(32),
>                parent integer);
>
> INSERT INTO tb VALUES(1, 'iPhone',    NULL);
> INSERT INTO tb VALUES(2, 'HTC',       NULL);
> INSERT INTO tb VALUES(3, 'Motorola',  NULL);
> INSERT INTO tb VALUES(4, 'iPhone3GS', 1);
> INSERT INTO tb VALUES(5, 'G7',        2);
> INSERT INTO tb VALUES(6, 'G8',        2);
> INSERT INTO tb VALUES(7, 'iPhone4',   1);
> INSERT INTO tb VALUES(8, 'iPhone4-white', 7);
> INSERT INTO tb VALUES(9, 'iPhone4-black', 7);
> INSERT INTO tb VALUES(10,'G7-A',      5);
> INSERT INTO tb VALUES(11,'G7-B',      5);
>
> *How to create a SQL to inquiry the result like this:*
> id       name
> ----------------
>  1        iPhone
>  4        iPhone3GS
>  7        iPhone4S
>  8        iPhone4S-white
>  9        iPhone4S-black
>  2        HTC
>  5        G7
> 10        G7-A
> 11        G7-B
>  3        Motorola
>
> Thank you very much!
>
>

postgres=# with recursive x as (select tb.*, tb.id::text as path
from tb
where parent is null
union all
select tb.*, path ||'|'
|| tb.id
from tb
join x
on tb.parent = x.id)
select id, name from x order by path;
id │ name
────┼───────────────
1 │ iPhone
4 │ iPhone3GS
7 │ iPhone4
8 │ iPhone4-white
9 │ iPhone4-black
2 │ HTC
5 │ G7
10 │ G7-A
11 │ G7-B
6 │ G8
3 │ Motorola
(11 rows)

>
>
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