如何在类别表中使用数据列表控件 [英] how to use datalist control in case Category Table

问题描述

我有这个sql语句......

I have this sql statement......

create table categories
( id       integer     not null  primary key
, name     varchar(37) not null
, parentid integer     null
, foreign key parentid_fk (parentid)
      references categories (id)
);

我想先显示其父级，然后单击父级以显示其子类别
使用数据列表.我有类似
的数据

And i wanna display its Parent first and by clicking parent show its sub category
using datalist.. I''ve data like

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

有人帮我吗...
在此先谢谢您

Is anyone help me...
Thank you in advance

推荐答案

您可以在两个sql语句中完成此操作.

以下查询将获取您的所有父类别.

Hi,

You can do it in two sql statements.

The below query will get all your parent categories.

Select id, name from categories where parentid is NULL

然后，当用户选择一个类别时，您便知道其ID，因此只需选择所有父类别与所选类别匹配的子类别.

Then when the user selects a category you know its Id, so then you just select all the child categories which have a parent category matching the selected category.

//Pass in parameter @ParentId which matches the Category clicked.
Select id, name from categories where parentid = @ParentId

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