PHP 改变查询结果的数组格式，效率问题

Question

$courseDetail = M('course')
            ->field('c.course_id,c.name,from_unixtime(c.time) as course_time,c.room_id,tu.teacher_id,tu.relname as teacher_name, tu.mobile as teacher_mobile,su.student_id,su.nickname as student_name,su.mobile as student_mobile')
            ->alias('c')
            ->join('left join __USER_COURSE__ uc using(course_id)')
            ->join('left join __TEACHER_USER__ tu on c.teacher_id = tu.teacher_id')
            ->join('left join __STUDENT_USER__ su on uc.user_id = su.student_id')
            ->where($cond)
            ->order('time '.$order)
            ->select();
        if (!$courseDetail){
            $data = '暂无课程';
        }else{
            $data = [];
            $tmp = $courseDetail;
            foreach ($courseDetail as $key => &$value){
                $course_id = $value['course_id'];
                $value['students'] = array(
                    array(
                        "student_id"    => $value['student_id'],
                        "name" => $value['student_name'],
                        "mobile"    => $value['student_mobile']
                    )
                );
                foreach($tmp as $k => $v){
                    if ($course_id == $v['course_id'] && $v['student_id'] != $value['student_id']){
                        $arr = array(
                            "student_id"    => $v['student_id'],
                            "name" => $v['student_name'],
                            "mobile"    => $v['student_mobile']
                        );
                        array_push($value['students'],$arr);
                        unset($courseDetail[$k]);
                    }
                }
                unset($value['student_id'],$value['student_name'],$value['student_mobile']);
                $data[] = $value;
            }
        }

我用的框架是ThinkPHP 其中刚查询出来的值 $courseDetail 的格式如下

        
array(5) {
  [0]=>
  array(10) {
    ["course_id"]=>
    string(4) "5202"
    ["name"]=>
    string(6) "暂无"
    ["course_time"]=>
    string(19) "2018-03-31 11:00:00"
    ["room_id"]=>
    string(25) "264_2018-03-31 11:00_manu"
    ["teacher_id"]=>
    string(3) "264"
    ["teacher_name"]=>
    string(12) "师零零贰"
    ["teacher_mobile"]=>
    string(11) "13900139002"
    ["student_id"]=>
    string(3) "272"
    ["student_name"]=>
    string(12) "学零零壹"
    ["student_mobile"]=>
    string(11) "13800138001"
  }
  [1]=>
  array(10) {
    ["course_id"]=>
    string(4) "5230"
    ["name"]=>
    string(6) "测试"
    ["course_time"]=>
    string(19) "2018-03-30 23:00:00"
    ["room_id"]=>
    string(25) "290_2018-03-30 23:00_4oBF"
    ["teacher_id"]=>
    string(3) "290"
    ["teacher_name"]=>
    string(15) "教师零叁零"
    ["teacher_mobile"]=>
    string(11) "13900139030"
    ["student_id"]=>
    string(3) "367"
    ["student_name"]=>
    string(12) "学零伍零"
    ["student_mobile"]=>
    string(11) "13800138050"
  }
  [2]=>
  array(10) {
    ["course_id"]=>
    string(4) "5230"
    ["name"]=>
    string(6) "测试"
    ["course_time"]=>
    string(19) "2018-03-30 23:00:00"
    ["room_id"]=>
    string(25) "290_2018-03-30 23:00_4oBF"
    ["teacher_id"]=>
    string(3) "290"
    ["teacher_name"]=>
    string(15) "教师零叁零"
    ["teacher_mobile"]=>
    string(11) "13900139030"
    ["student_id"]=>
    string(3) "276"
    ["student_name"]=>
    string(12) "学零零叁"
    ["student_mobile"]=>
    string(11) "13800138003"
  }
  [3]=>
  array(10) {
    ["course_id"]=>
    string(4) "5229"
    ["name"]=>
    string(6) "测试"
    ["course_time"]=>
    string(19) "2018-03-30 22:30:00"
    ["room_id"]=>
    string(25) "290_2018-03-30 22:30_TQ8o"
    ["teacher_id"]=>
    string(3) "290"
    ["teacher_name"]=>
    string(15) "教师零叁零"
    ["teacher_mobile"]=>
    string(11) "13900139030"
    ["student_id"]=>
    string(3) "367"
    ["student_name"]=>
    string(12) "学零伍零"
    ["student_mobile"]=>
    string(11) "13800138050"
  }
  [4]=>
  array(10) {
    ["course_id"]=>
    string(4) "5228"
    ["name"]=>
    string(6) "测试"
    ["course_time"]=>
    string(19) "2018-03-30 22:00:00"
    ["room_id"]=>
    string(25) "290_2018-03-30 22:00_4PBm"
    ["teacher_id"]=>
    string(3) "290"
    ["teacher_name"]=>
    string(15) "教师零叁零"
    ["teacher_mobile"]=>
    string(11) "13900139030"
    ["student_id"]=>
    string(3) "367"
    ["student_name"]=>
    string(12) "学零伍零"
    ["student_mobile"]=>
    string(11) "13800138050"
  }
}

但是这种格式有一个问题 course_id与student_id是一个一对多的关系，这样查询出来的数据就会有course_id和teacher_id相等的几个数据，我现在想把数据按course_id归成一条 就写了上面的循环，$data结果如下：

array(4) {
  [0]=>
  array(8) {
    ["course_id"]=>
    string(4) "5202"
    ["name"]=>
    string(6) "暂无"
    ["course_time"]=>
    string(19) "2018-03-31 11:00:00"
    ["room_id"]=>
    string(25) "264_2018-03-31 11:00_manu"
    ["teacher_id"]=>
    string(3) "264"
    ["teacher_name"]=>
    string(12) "师零零贰"
    ["teacher_mobile"]=>
    string(11) "13900139002"
    ["students"]=>
    array(1) {
      [0]=>
      array(3) {
        ["student_id"]=>
        string(3) "272"
        ["name"]=>
        string(12) "学零零壹"
        ["mobile"]=>
        string(11) "13800138001"
      }
    }
  }
  [1]=>
  array(8) {
    ["course_id"]=>
    string(4) "5230"
    ["name"]=>
    string(6) "测试"
    ["course_time"]=>
    string(19) "2018-03-30 23:00:00"
    ["room_id"]=>
    string(25) "290_2018-03-30 23:00_4oBF"
    ["teacher_id"]=>
    string(3) "290"
    ["teacher_name"]=>
    string(15) "教师零叁零"
    ["teacher_mobile"]=>
    string(11) "13900139030"
    ["students"]=>
    array(2) {
      [0]=>
      array(3) {
        ["student_id"]=>
        string(3) "367"
        ["name"]=>
        string(12) "学零伍零"
        ["mobile"]=>
        string(11) "13800138050"
      }
      [1]=>
      array(3) {
        ["student_id"]=>
        string(3) "276"
        ["name"]=>
        string(12) "学零零叁"
        ["mobile"]=>
        string(11) "13800138003"
      }
    }
  }
  [2]=>
  array(8) {
    ["course_id"]=>
    string(4) "5229"
    ["name"]=>
    string(6) "测试"
    ["course_time"]=>
    string(19) "2018-03-30 22:30:00"
    ["room_id"]=>
    string(25) "290_2018-03-30 22:30_TQ8o"
    ["teacher_id"]=>
    string(3) "290"
    ["teacher_name"]=>
    string(15) "教师零叁零"
    ["teacher_mobile"]=>
    string(11) "13900139030"
    ["students"]=>
    array(1) {
      [0]=>
      array(3) {
        ["student_id"]=>
        string(3) "367"
        ["name"]=>
        string(12) "学零伍零"
        ["mobile"]=>
        string(11) "13800138050"
      }
    }
  }
  [3]=>
  array(8) {
    ["course_id"]=>
    string(4) "5228"
    ["name"]=>
    string(6) "测试"
    ["course_time"]=>
    string(19) "2018-03-30 22:00:00"
    ["room_id"]=>
    string(25) "290_2018-03-30 22:00_4PBm"
    ["teacher_id"]=>
    string(3) "290"
    ["teacher_name"]=>
    string(15) "教师零叁零"
    ["teacher_mobile"]=>
    string(11) "13900139030"
    ["students"]=>
    array(1) {
      [0]=>
      array(3) {
        ["student_id"]=>
        string(3) "367"
        ["name"]=>
        string(12) "学零伍零"
        ["mobile"]=>
        string(11) "13800138050"
      }
    }
  }
}

我感觉我写的方法有问题 效率低，代码质量比较差，但又想不出其他方法。想问问大家有没有更好的方法，谢谢！