Php 通过对匹配值进行分组来循环数组

我正在为我的网站写一个模块，它给出了测试结果的分类，我需要得到类似的结果

考试题目 平均得分85%

测试标题2 平均分数12%

我从数据库中获取的数组如下所示

    Array
(
    [0] => Array
        (
            [result_id] => 11
            [test_taken] => 2011-10-04 16:22:59
            [mark] => 5
            [retaken] => false
            [tests_test_id] => 4
            [test_title] => Website Development CSS Basics
            [test_slug] => website-development-css-basics
            [mark_needed] => 90
            [retake] => Yes
            [topic_id] => 402
            [topics_topic_id] => 402
        )

    [1] => Array
        (
            [result_id] => 12
            [test_taken] => 2011-10-04 16:30:02
            [mark] => 50
            [retaken] => false
            [tests_test_id] => 5
            [test_title] => Another Test
            [test_slug] => another-test
            [mark_needed] => 10
            [retake] => No
            [topic_id] => 402
            [topics_topic_id] => 402
        )

)

这是我目前的疑问,

$this->db->select('results.result_id, results.test_taken, results.mark, results.retaken, results.tests_test_id, tests.test_title, tests.test_slug, tests.mark_needed, tests.retake, topics.topic_id, tests.topics_topic_id')
    ->from('results')
    ->join('tests', 'tests.test_id = results.tests_test_id', 'left')
    ->join('topics', 'topics.topic_id = tests.topics_topic_id', 'left');

    $query = $this->db->get();
    return $query->result_array();

我需要以某种方式将所有具有相同测试id的结果分组，这样我就可以使用mark键获得结果的平均值

---

这在PHP中可能吗？

这是您应该让数据库为您做的事情。大致如下：

SELECT AVG(mark) FROM test_results GROUP BY tests_test_id

---

创建一个新数组，然后循环-边添加边执行

$sumArray = array();

foreach ($myArray as $key=>$val) {
    $sumArray[$key]+=$val;
}

print_r($sumArray['test_id']);

---

你可以用更聪明的质问来回答