public function echo_sql() {
        $A_LIST = M('driver')->limit(10)->select();
        $sql = $this->add_sql('driver', $A_LIST, '');
    }
    public function add_sql($table, $info, $sql) {
        $sql = '';
        foreach ($info as $val) {
            $sql .= 'insert into hd_'.$table.' (';
            $left = '';
            $right = '';
            foreach ($val as $k=>$v) {
                $left .= $k.',';
                $right .= '\''.$v.'\',';
            }
            $left = rtrim($left, ',');
            $right = rtrim($right, ',');
            $sql .= $left.') values ('.$right.');'.'<br/>';
        }
        return $sql;
    }