php - 从一个表中按“父ID”排序选择数据

您能帮我写SQL select吗？

我有桌子：

地区


id（int）
名称（varchar（50））
parent_id（int）


其中“ parent_id”是指“ id”。 parent_id设置为0的行没有父行，位于最上面。我需要选择数据作为树。

知道我使用递归函数:)

function SelectData($parent=0, $padding='')
{
 $q = mysql_query("SELECT * FROM regions WHERE parent=$parent");
 while($row = mysql_fetcharray($q))
 {
  echo($row[name]);
  priklad($row[id], $padding.'  ');
 }
}

我发现可以使用CTE（Can I select full hierarchy of parents when id and parent id are in the same table?），但是还发现MySQL不支持CTE。

那么，有没有办法在MySQL中使用单选而不是递归函数？
谢谢 ：）

最佳答案

您可以使用非递归的mysql存储过程，可以从php调用它，如下所示：

呼叫范例

$result = $conn->query(sprintf("call category_hier(%d)", $catID));

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 |
|      5 | Chicago       |             3 | USA                  |     2 |
|      4 | Illinois      |             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)

完整的脚本和测试数据如下

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);


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 tmp on c.parent_cat_id = tmp.cat_id and tmp.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 ;

call category_hier(1);

call category_hier(2);

希望这可以帮助 ：）

关于php - 从一个表中按“父ID”排序选择数据，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/5566924/