一个无限分类的实现原理

一个无限分类的实现原理（注意只是原理，许多类的引用都被我去掉了） [PHP]   function toggleShowCascade(idshow,idfocus) { resetCascadeFocus(); if(idshow!='') with (document.getElementById(idshow).style) { if(display=='') display='none'; else display=''; } document.getElementById(idfocus).className='idfocus'; } function iniCascadeHide() { for(i=0;i
body
{
        background-color: #dadada;
        border-bottom: #8f8f8f 1px solid;
        border-left: #f0efef 1px solid;
        border-right: #8f8f8f 1px solid;
        border-top: #f0efef 1px solid;
        font-family: 宋体;
        font-size: 9pt;
        font-style: normal;
        font-weight: normal;
        margin: 0px;
        padding-bottom: 0px;
        padding-left: 0px;
        padding-right: 0px;
        padding-top: 0px;
        scrollbar-face-color: #666666;
        scrollbar-shadow-color: #dddddd;
        scrollbar-3dlight-color: #666666;
        scrollbar-arrow-color: #dddddd;
        scrollbar-track-color: #666666;
        scrollbar-darkshadow-color: #666666;
}
body,td,th
{
        font-family: "新宋体";
        font-size: 12px;
        font-style: normal;
        line-
}
span img{margin-left:18}
span span img{margin-left:34}
span span span img{margin-left:50}
span span span span img{margin-left:66}
span span span span span img{margin-left:82}
span span span span span span img{margin-left:98}
/*
This block should contain as many lines as total layers of sub-categories, with
each line inserting an additional span beforehand, and an increment of 16px of
left-margin(which is accustomed to your configuration).
*/
.idfocus
{
        background-color: blue;
        color:white;
        padding:1;
        text-decoration: none;
}
.block
{
        text-decoration: none;
}
.tbl_block
{
        background-color: #808080;
}
table.tbl_block th
{
        background-color: #c0c0c0;
}
.tr2
{
        background-color: #abb7d3;
}
.tr1
{
        background-color: #dadada;
}
.abcdefg
{
        background-color: blue;
        filter: DropShadow(Color=#ffffff, offX=1, offY=1);
        text-decoration: none;
}
'; $str3 =getChild($arr,$arr[$i][2],$depth+1); $str2.=$str3; $str2.=$space.""; if($str3=='') $str.= $space.'

'.$str2; else $str.= $space.'

'.$str2; } } return $str; } echo getChild($block,0)."
\n\n"; ?>
next
CREATE TABLE `block` (
`tid` int(10) NOT NULL auto_increment,
`name` varchar(20) NOT NULL default '',
`admin` int(10) NOT NULL default '0',
`parent` int(10) NOT NULL default '0',
`birth` date NOT NULL default '0000-00-00',
`remark` varchar(200) NOT NULL default '',
`level` smallint(4) NOT NULL default '0',
`flag` enum('1','0') NOT NULL default '1',
UNIQUE KEY `tid` (`tid`)
) TYPE=MyISAM ROW_FORMAT=DYNAMIC COMMENT='论坛或栏目版块设置';
#
# Dumping data for table 'block'
#
INSERT INTO block VALUES("1", "PHP社区", "1", "0", "2004-04-25", "", "0", "1");
INSERT INTO block VALUES("2", "操作系统", "2", "0", "2004-04-25", "", "0", "1");
INSERT INTO block VALUES("3", "影视娱乐", "3", "0", "2004-04-25", "", "0", "1");
INSERT INTO block VALUES("4", "人文科学", "4", "0", "2004-04-25", "", "0", "1");
INSERT INTO block VALUES("5", "作品交流", "5", "0", "2004-04-25", "", "0", "1");
INSERT INTO block VALUES("6", "原创代码", "6", "5", "2004-04-25", "", "0", "1");
INSERT INTO block VALUES("7", "系统集成代码", "7", "5", "2004-04-25", "", "0", "1");
INSERT INTO block VALUES("8", "共享软件", "8", "5", "2004-04-25", "", "0", "1");
INSERT INTO block VALUES("9", "经典名曲", "9", "3", "2004-04-25", "", "0", "1");
INSERT INTO block VALUES("10", "海外文学", "10", "3", "2004-04-25", "", "0", "1");
INSERT INTO block VALUES("11", "英美散文", "11", "3", "2004-04-25", "", "0", "1");
INSERT INTO block VALUES("12", "古典文学", "12", "3", "2004-04-25", "", "0", "1");
INSERT INTO block VALUES("13", "系统工具", "13", "8", "2004-04-25", "", "0", "1");
INSERT INTO block VALUES("14", "图片处理", "14", "8", "2004-04-25", "", "0", "1");
INSERT INTO block VALUES("15", "文字编辑", "15", "8", "2004-04-25", "", "0", "1");
INSERT INTO block VALUES("16", "影音娱乐", "16", "8", "2004-04-25", "", "0", "1");
INSERT INTO block VALUES("17", "系统扫描工具", "17", "13", "2004-04-25", "", "0", "1");
INSERT INTO block VALUES("18", "网络监视工具", "18", "13", "2004-04-25", "", "0", "1");
INSERT INTO block VALUES("19", "局域网管理", "19", "18", "2004-04-25", "", "0", "1");
INSERT INTO block VALUES("20", "因特网搜索", "20", "18", "2004-04-25", "", "0", "1");
INSERT INTO block VALUES("21", "搜索引擎", "21", "20", "2004-04-25", "", "0", "1");
INSERT INTO block VALUES("22", "PHP搜索引擎", "22", "21", "2004-04-25", "", "0", "1");