求好的步骤~

INSERT INTO `vm_nav` (`id`, `ctype`, `cid`, `name`, `ifshow`, `vieworder`, `opennew`, `url`, `type`) VALUES
(1, NULL, 0, 'index', 0, 1, 0, '', 'nav'),
(2, NULL, 0, 'product', 1, 2, 0, '', 'nav'),
(3, NULL, 0, 'member', 1, 3, 0, '', 'nav'),
(4, NULL, 0, 'guide', 1, 4, 0, '', 'nav'),
(5, NULL, 0, 'kehu', 1, 5, 0, '', 'nav'),
(6, NULL, 0, 'about', 1, 6, 0, '', 'nav'),
(7, NULL, 0, 'tehui', 1, 7, 0, '', 'nav'),
(8, NULL, 3, 'member_index', 1, 1, 0, '', 'nav'),
(9, NULL, 3, 'member_info', 1, 2, 0, '', 'nav');

array(8) {
  [0]=>
  array(6) {
    ["id"]=>
    string(1) "2"
    ["name"]=>
    string(12) "product"
    ["opennew"]=>
    string(1) "0"
    ["url"]=>
    string(0) ""
    ["ctype"]=>
    NULL
    ["cid"]=>
    string(1) "0"
  }
  [1]=>
  array(6) {
    ["id"]=>
    string(1) "3"
    ["name"]=>
    string(18) "member"
    ["opennew"]=>
    string(1) "0"
    ["url"]=>
    string(0) ""
    ["ctype"]=>
    NULL
    ["cid"]=>
    string(1) "0"
  }
  [2]=>
  array(6) {
    ["id"]=>
    string(1) "8"
    ["name"]=>
    string(12) "member_index"
    ["opennew"]=>
    string(1) "0"
    ["url"]=>
    string(0) ""
    ["ctype"]=>
    NULL
    ["cid"]=>
    string(1) "3"
  }
  [3]=>
  array(6) {
    ["id"]=>
    string(1) "9"
    ["name"]=>
    string(12) "member_info"
    ["opennew"]=>
    string(1) "0"
    ["url"]=>
    string(0) ""
    ["ctype"]=>
    NULL
    ["cid"]=>
    string(1) "3"
  }
  [4]=>
  array(6) {
    ["id"]=>
    string(1) "4"
    ["name"]=>
    string(12) "guide"
    ["opennew"]=>
    string(1) "0"
    ["url"]=>
    string(0) ""
    ["ctype"]=>
    NULL
    ["cid"]=>
    string(1) "0"
  }
  [5]=>
  array(6) {
    ["id"]=>
    string(1) "5"
    ["name"]=>
    string(12) "kehu"
    ["opennew"]=>
    string(1) "0"
    ["url"]=>
    string(0) ""
    ["ctype"]=>
    NULL
    ["cid"]=>
    string(1) "0"
  }
  [6]=>
  array(6) {
    ["id"]=>
    string(1) "6"
    ["name"]=>
    string(12) "about"
    ["opennew"]=>
    string(1) "0"
    ["url"]=>
    string(0) ""
    ["ctype"]=>
    NULL
    ["cid"]=>
    string(1) "0"
  }
  [7]=>
  array(6) {
    ["id"]=>
    string(1) "7"
    ["name"]=>
    string(12) "tehui"
    ["opennew"]=>
    string(1) "0"
    ["url"]=>
    string(0) ""
    ["ctype"]=>
    NULL
    ["cid"]=>
    string(1) "0"
  }
}

function nav_list(){
    $navlist = get_navigator();
    sort($navlist['nav']);
   //$navlist['nav']  就是取出所有数据 ，上面用sort排了下序
    foreach($navlist['nav'] as $k=>$v)
    {
        if($v['cid'] != 0)
        {
            //插入到一个son成员里
            $l[$v['cid']]['son'][] = $v;
            
        }else{
        	$l[$v['id']] = $v;
        }
    }
    foreach($l as $k=>$v){
        if($v['son']){
            //消除son成员
            $tmp[] = array_diff_key($v,array('son'=>''));
            foreach($v['son'] as $key=>$val){
                //再一个foreach 放到其后面
                $tmp[] = $val;
            }
        }else{
            $tmp[] = $v;
        }
    }
    return $tmp;
}

select id, ctype, cid, name, ifshow, vieworder, opennew, url, type from vm_nav where ifshow and cid=0
union
select cid as id, ctype, cid, name, ifshow, vieworder, opennew, url, type from vm_nav where ifshow and cid>0
order by id