使用PHP和MySQL设计应用程序,帮助教师进行在线多项选择测试。每个考试有100个问题,每个问题有4个以上的选择。
当超过1000名用户参加考试时,当系统管理员进入“统计”以查看平均分数或其他统计数据时,经过大量思考后,系统不会显示任何内容:没有结果,没有统计数据
计算:100个问题* 4个选择* 1000个用户获得平均分数。
当我们在更强大的PC上运行Web服务器时,它会显示统计信息,但在共享服务器中它不显示任何内容。
表架构是InnoDB。
如何计算平均分数和/或将结果导出到CSV文件,或将它们添加到数组并对其进行排序?
这是在导出到csv文件之前计算最终得分的代码:
$result_list = array();
foreach($UserTestList as $userTestProp)
{
$result_list[$userTestProp['utid']]=array();
....
$result_list[$userTestProp['utid']]['utid'] = $userTestProp['utid'];
$result_list[$userTestProp['utid']]['utlength'] = gmdate("H:i:s", strtotime($userTestProp['utlast_activity'])-strtotime($userTestProp['utstart_datetime']));
$result_list[$userTestProp['utid']]['utuser_ip'] = $userTestProp['utuser_ip'];
$result_list[$userTestProp['utid']]['utbrowser'] = $userTestProp['utbrowser'];
...
$result_list[$userTestProp['utid']]['correct'] = $test->GetNumOfAnswers('correct',$userTestProp['utid']);
$result_list[$userTestProp['utid']]['incorrect'] = $test->GetNumOfAnswers('incorrect',$userTestProp['utid']);
$result_list[$userTestProp['utid']]['none'] = $test->GetNumOfAnswers('none',$userTestProp['utid']);
$result_list[$userTestProp['utid']]['final_score'] = ($testInfo['tminus_mark']==1?round(($result_list[$userTestProp['utid']]['correct']-($result_list[$userTestProp['utid']]['incorrect']/3)),2):$result_list[$userTestProp['utid']]['correct']);
}
这里是GetNumOfAnswers方法:
function GetNumOfAnswers($type,$utid)
{
global $table_prefix;
$total_correct_answers=$total_incorrect_answers=$total_none_answered=0;
$QuestionList = $this->GetLessonQuestionListByUTID($utid,NULL);
foreach ($QuestionList as $QuestionInfo)
{
switch ($this->IsCorrect($utid,$QuestionInfo['qid']))
{
case '1':
$total_correct_answers++;
break;
case '0':
$total_incorrect_answers++;
break;
default:
$total_none_answered++;
break;
}
}
switch ($type) {
case 'correct':
return $total_correct_answers;
break;
case 'incorrect':
return $total_incorrect_answers;
break;
case 'none':
return $total_none_answered;
break;
case 'all':
return count($QuestionList);
break;
}
}
这里是IsCorrect方法:
function IsCorrect($utid,$qid)
{
global $table_prefix;
$query = $this->link->prepare("SELECT `qcid` FROM `".$table_prefix."user_test_question` INNER JOIN `".$table_prefix."user_test_question_choice`
ON `".$table_prefix."user_test_question`.`utqid`=`".$table_prefix."user_test_question_choice`.`utqid` WHERE `utid`=? AND `qid`=?");
$values = array($utid,$qid);
$query->execute($values);
$qcid_chosen = $query->fetchAll();
if(empty($qcid_chosen))
return 2;
$query = $this->link->prepare("SELECT `qcid` FROM `".$table_prefix."questions` INNER JOIN `".$table_prefix."questions_choices`
ON `".$table_prefix."questions`.`qid`=`".$table_prefix."questions_choices`.`qid` WHERE `".$table_prefix."questions`.`qid`=? AND `qcis_answer`=1");
$values = array($qid);
$query->execute($values);
$qcid_correct = $query->fetchAll();
if ($qcid_chosen==$qcid_correct)
return 1;
else
return 0;
return $counts;
}
答案 0 :(得分:0)
您的结构/应用中肯定存在一些设计缺陷。 MySQL我非常有能力计算大数据集的平均值。
您的数据结构是否方便安排以获得最简单的阅读效果?
您的表是否在最常读的列上编入索引?
您的应用程序平均逻辑是否在MySQL中作为一个查询运行?还是用PHP运行?
如果它在PHP中运行,那么很可能你的共享托管环境有一个超出你的PHP memory_limit(因为你试图从MySQL中读取大量数据到PHP及其过程)。