Hello
2011/11/10 shuaixf <shuaixf@gmail.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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>
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