读取树状数据的方法
读取树状数据的方法
一般在读取用“邻接列表算法”组织的数据时，需要使用递归逐层读取
或者读取数据到数组，然后用递归或非递归的方法再行处理
这里介绍一种边读边生成“树状”数组的方法
mysql_connect();
//测试数据
$sql =<<< SQL
select * from (
select '1' as id, '0' as pid, 'Food' as title
union all select '2', '1', 'Fruit'
union all select '3', '2', 'Red'
union all select '4', '3', 'Cherry'
union all select '5', '2', 'Yellow'
union all select '6', '5', 'Banana'
union all select '7', '1', 'Meat'
union all select '8', '7', 'Beef'
union all select '9', '7', 'Pork'
) t
order by pid, id
SQL;
$rs = mysql_query($sql);
$res = array(); //结果数组
$ind = array(); //索引数组
while($row = mysql_fetch_assoc($rs)) {
list($id, $pid) = array_values($row);
$ind[$id] = $row;
if(isset($ind[$pid])) $ind[$pid]['child'][$id] =& $ind[$id]; //构造索引
if($pid == 0) $res[$id] =& $ind[$id]; //转存根节点组
}
echo '<xmp>' . print_r($res, 1);
Array
(
[1] => Array
(
[id] => 1
[pid] => 0
[title] => Food
[child] => Array
(
[2] => Array
(
[id] => 2
[pid] => 1
[title] => Fruit
[child] => Array
(
[3] => Array
(
[id] => 3
[pid] => 2
[title] => Red
[child] => Array
(
[4] => Array
(
[id] => 4
[pid] => 3
[title] => Cherry
)
)
)
[5] => Array
(
[id] => 5
[pid] => 2
[title] => Yellow
[child] => Array
(
[6] => Array
(
[id] => 6
[pid] => 5
[title] => Banana
)
)
)
)
)
[7] => Array
(
[id] => 7
[pid] => 1
[title] => Meat
[child] => Array
(
[8] => Array
(
[id] => 8
[pid] => 7
[title] => Beef
)
[9] => Array
(
[id] => 9
[pid] => 7
[title] => Pork
)
)
)
)
)
)
