一、无限级分类
 -- 创建表
create table it_category (
cat_id int unsigned primary key auto_increment,
cat_name varchar(50) default ‘‘,
sort_order int default 0,
parent_id int unsigned
);
-- 插入记录
insert into it_category values (75, ‘分类KKK‘, 50, 0);
insert into it_category values (12, ‘分类FFF‘, 50, 75);
insert into it_category values (77, ‘分类AAA‘, 50, 75);
insert into it_category values (34, ‘分类XXX‘, 50, 12);
insert into it_category values (35, ‘分类HHH‘, 50, 12);
insert into it_category values (9, ‘分类QQQ‘, 50, 77);
insert into it_category values (28, ‘分类JJJ‘, 50, 35);
insert into it_category values (19, ‘分类MMM‘, 50, 35);

<?php
//一、这是老师讲的
//首先，得到所有分类数据
mysql_connect(‘127.0.0.1:3306‘, ‘root‘, ‘1234abcd‘);
$sql = "select * from itcast_shop.it_category where 1 order by sort_order";
$result = mysql_query($sql);
while ($row = mysql_fetch_assoc($result)) {
    $list[] = $row;
}

//然后，调用递归查找函数
$tree = getTree($list, 0, 0);

//最后，遍历显示
foreach ($tree as $row) {
    echo str_repeat(‘&nbsp;&nbsp;‘, $row[‘deep‘]);
    echo $row[‘cat_name‘];
    echo ‘<br>‘;
}

function getTree($arr, $p_id, $deep = 0) {
    static $tree = array();
    foreach ($arr as $row) {
        if ($row[‘parent_id‘] == $p_id) {
            $row[‘deep‘] = $deep;
            $tree[] = $row;
            //找到了一条符合条件的，马上递归向更深层次查找！查找完毕再回来继续本foreach
            getTree($arr, $row[‘cat_id‘], $deep + 1);
        }
    }

    //foreach执行完毕，返回结果
    return $tree;
}


---------------------------------换个方法------------------------------


<?php

//二、有朋友迷惑于递归函数的return $tree;
//其实递归进去以后，这个return没什么用，因为$tree已经是静态局部变量
//return的作用是foreach执行完毕，返回查找到的数据
//*我们不用return，把$tree作为超全局变量看看
//首先，得到所有分类数据
mysql_connect(‘127.0.0.1:3306‘, ‘root‘, ‘1234abcd‘);
$sql = "select * from itcast_shop.it_category where 1 order by sort_order";
$result = mysql_query($sql);
while ($row = mysql_fetch_assoc($result)) {
    $list[] = $row;
}

//然后，调用递归查找函数
getTree($list, 0, 0);

//最后，遍历显示
foreach ($tree as $row) {
    echo str_repeat(‘&nbsp;&nbsp;‘, $row[‘deep‘]);
    echo $row[‘cat_name‘];
    echo ‘<br>‘;
}

function getTree($arr, $p_id, $deep = 0) {
    foreach ($arr as $row) {
        if ($row[‘parent_id‘] == $p_id) {
            $row[‘deep‘] = $deep;
            $GLOBALS[‘tree‘][] = $row;
            //找到了一条符合条件的，马上递归向更深层次查找！查找完毕再回来继续本foreach
            getTree($arr, $row[‘cat_id‘], $deep + 1);
        }
    }
}




二、用php实现打印磁盘文件目录
<?php
function dirTree($path, $deep = 0) {
    $dir_handle = opendir($path);

    while (($file = readdir($dir_handle)) !== FALSE) {
        if ($file == ‘.‘ || $file == ‘..‘) {

        } else {
            if (is_dir($path . ‘/‘ . $file)) {
                echo str_repeat(‘&nbsp;&nbsp;&nbsp;‘, $deep);
                echo ‘+‘, $file, ‘<br />‘;
                dirTree($path . ‘/‘ . $file, $deep + 1);
            } else {
                echo str_repeat(‘&nbsp;&nbsp;&nbsp;‘, $deep);
                echo $file, ‘<br />‘;
            }
        }
    }
}

$path = ‘D:\amp\apache\htdocs\study‘;
dirTree($path);

无限级分类和打印磁盘文件目录