数据库分类查询有关问题

<br />
SELECT * from good<br />
ORDER BY series<br />

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<br />
static function GetTree($depth, $parentID, $nodeID)<br />
    {<br />
<br />
        $str = "";<br />
        $nodes = D_node::GetListAll("where parentid=" . $parentID . "", "orderflag desc");<br />
        if (count($nodes) > 0) {<br />
            foreach ($nodes as $node) {<br />
                $str .= self::GetPrefixString($depth) . $node->nodename;<br />
                $str .= self::GetTree($depth + 1, $node->id, $nodeID);<br />
            }<br />
        }<br />
<br />
<br />
        return $str;<br />
    }<br />
    static function GetPrefixString($depth)<br />
    {<br />
<br />
        $str = "--";<br />
        for ($i = 0; $i < $depth; $i++) {<br />
            $str .= "--";<br />
<br />
        }<br />
        return $str;<br />
    }<br />