Php 类别和子类别的递归函数
我需要关于递归函数的帮助,我们有一个包含category\u id、category\u name和parent\u id的category表:Php 类别和子类别的递归函数,php,mysql,recursion,categories,Php,Mysql,Recursion,Categories,我需要关于递归函数的帮助,我们有一个包含category\u id、category\u name和parent\u id的category表: category_id category_name parent_id ------------+--------------+---------- 1 Agriculture 0 2 Appearl & Fashion 0 3 Chemicalas 0 4 Plastic & Plastic Products 0 5 Au
category_id category_name parent_id
------------+--------------+----------
1 Agriculture 0
2 Appearl & Fashion 0
3 Chemicalas 0
4 Plastic & Plastic Products 0
5 Automobile 0
14 Coconut Shell Products 1
15 Nuts & Kernels 1
16 Plant & Animal Oil 1
17 Potpourri 1
18 Raw Cotton & Cotton Waste 1
19 Rice 1
20 Tea 1
21 Seeds 1
22 Vegetable 1
23 White Rice 19
24 Green Rice 19
25 Basmati Rice 19
26 Boiled Rice 19
27 Fresh Preserved Vegetables 22
28 Frozen & Dried Vegetables 22
29 Others 22
30 Activated Carbon 3
我们希望使用递归函数得到如下类别的输出:
Agriculture > Rice > White rice
Agruculture > Rice > Basmati rice
请。引导并帮助我什么
function recursiveCategory($categoryId) {
// Some code to get category from the database resulting in Category-array
$content = $Category["category_name"];
if($Category["category_parent"] == 0) {
$content .= " > ".$recursiveCategory($Category["category_parent"]);
}
return $content;
}
此外,如果类别没有父项,则不要在父项id中使用值0。请改用
null
。尽管它与表中的模式不完全相同,但它对于执行类似于您尝试执行的操作非常有用。读一读,看看你是怎么想的,这对我第一次尝试像你这样的树结构真的很有帮助。使用非递归/邻接列表存储过程实现从PHP到MySQL的一次调用非常简单
希望有帮助:)
示例调用
mysql> call category_hier(1);
+--------+---------------+---------------+----------------------+-------+
| cat_id | category_name | parent_cat_id | parent_category_name | depth |
+--------+---------------+---------------+----------------------+-------+
| 1 | Location | NULL | NULL | 0 |
| 3 | USA | 1 | Location | 1 |
| 4 | Illinois | 3 | USA | 2 |
| 5 | Chicago | 3 | USA | 2 |
+--------+---------------+---------------+----------------------+-------+
4 rows in set (0.00 sec)
mysql> call category_hier(2);
+--------+---------------+---------------+----------------------+-------+
| cat_id | category_name | parent_cat_id | parent_category_name | depth |
+--------+---------------+---------------+----------------------+-------+
| 2 | Color | NULL | NULL | 0 |
| 6 | Black | 2 | Color | 1 |
| 7 | Red | 2 | Color | 1 |
+--------+---------------+---------------+----------------------+-------+
3 rows in set (0.00 sec)
$sqlCmd = sprintf("call category_hier(%d);", 1);
$sqlCmd = sprintf("call category_hier(%d);", 2);
表格和测试数据
drop table if exists categories;
create table categories
(
cat_id smallint unsigned not null auto_increment primary key,
name varchar(255) not null,
parent_cat_id smallint unsigned null,
key (parent_cat_id)
)
engine = innodb;
insert into categories (name, parent_cat_id) values
('Location',null),
('Color',null),
('USA',1),
('Illinois',3),
('Chicago',3),
('Black',2),
('Red',2);
存储过程
drop procedure if exists category_hier;
delimiter #
create procedure category_hier
(
in p_cat_id smallint unsigned
)
begin
declare v_done tinyint unsigned default 0;
declare v_depth smallint unsigned default 0;
create temporary table hier(
parent_cat_id smallint unsigned,
cat_id smallint unsigned,
depth smallint unsigned default 0
)engine = memory;
insert into hier select parent_cat_id, cat_id, v_depth from categories where cat_id = p_cat_id;
create temporary table tmp engine=memory select * from hier;
/* http://dev.mysql.com/doc/refman/5.0/en/temporary-table-problems.html */
while not v_done do
if exists( select 1 from categories c
inner join hier on c.parent_cat_id = hier.cat_id and hier.depth = v_depth) then
insert into hier select c.parent_cat_id, c.cat_id, v_depth + 1 from categories c
inner join tmp on c.parent_cat_id = tmp.cat_id and tmp.depth = v_depth;
set v_depth = v_depth + 1;
truncate table tmp;
insert into tmp select * from hier where depth = v_depth;
else
set v_done = 1;
end if;
end while;
select
c.cat_id,
c.name as category_name,
p.cat_id as parent_cat_id,
p.name as parent_category_name,
hier.depth
from
hier
inner join categories c on hier.cat_id = c.cat_id
left outer join categories p on hier.parent_cat_id = p.cat_id
order by
hier.depth;
drop temporary table if exists hier;
drop temporary table if exists tmp;
end #
delimiter ;
请张贴你尝试过的内容,以及你被困的具体位置。