这不是一个重复的问题，因为上面的链接只是创建了我试图回答的相同问题
我在 phpmyadmin 中有一个简单的表，由类别 id、类别名称及其父类别 id 组成，因此列标记为：id、name、parentid
示例数据：
id name parentid
1 animal NULL
2 vegetable NULL
3 mineral NULL
4 doggie 1
5 kittie 1
6 horsie 1
7 gerbil 1
8 birdie 1
9 carrot 2
10 tomato 2
11 potato 2
12 celery 2
13 rutabaga 2
14 quartz 3
15 feldspar 3
16 silica 3
17 gypsum 3
18 hunting 4
19 companion 4
20 herding 4
21 setter 18
22 pointer 18
23 terrier 18
24 poodle 19
25 chihuahua 19
26 shepherd 20
27 collie 20
我想输出所有类别路径和每个类别的 id。到目前为止，我可以使用以下 sql 创建路径：
select root.name as root_name
, down1.name as down1_name
, down2.name as down2_name
, down3.name as down3_name
from categories as root
left outer
join categories as down1
on down1.parentid = root.id
left outer
join categories as down2
on down2.parentid = down1.id
left outer
join categories as down3
on down3.parentid = down2.id
where root.parentid is null
order
by root_name
, down1_name
, down2_name
, down3_name
我想要添加到输出的是每个类别的 ID 及其路径。我在以下位置找到了上面的代码：http ://sqllessons.com/categories.html
上面的代码创建了以下内容：
root_name down1_name down2_name down3_name
animal birdie NULL NULL
animal doggie companion chihuahua
animal doggie companion poodle
animal doggie herding collie
animal doggie herding shepherd
animal doggie hunting pointer
animal doggie hunting setter
animal doggie hunting terrier
animal gerbil NULL NULL
animal horsie NULL NULL
animal kittie NULL NULL
mineral feldspar NULL NULL
mineral gypsum NULL NULL
mineral quartz NULL NULL
mineral silica NULL NULL
vegetable carrot NULL NULL
vegetable celery NULL NULL
vegetable potato NULL NULL
vegetable rutabaga NULL NULL
vegetable tomato NULL NULL
但是，我希望它创建以下内容：
id root_name down1_name down2_name down3_name
8 animal birdie NULL NULL
25 animal doggie companion chihuahua
24 animal doggie companion poodle
27 animal doggie herding collie
26 animal doggie herding shepherd
22 animal doggie hunting pointer
21 animal doggie hunting setter
23 animal doggie hunting terrier
7 animal gerbil NULL NULL
6 animal horsie NULL NULL
5 animal kittie NULL NULL
15 mineral feldspar NULL NULL
17 mineral gypsum NULL NULL
14 mineral quartz NULL NULL
16 mineral silica NULL NULL
9 vegetable carrot NULL NULL
12 vegetable celery NULL NULL
11 vegetable potato NULL NULL
13 vegetable rutabaga NULL NULL
10 vegetable tomato NULL NULL
请记住，以上内容来自上述链接，真实数据最多可包含 6 个级别的子类别。
谢谢你的帮助
约翰