循环只通过一组数据

时间：2013-02-08 19:04:21

标签： php mysqli

在一个或两个相关下拉菜单中选择All选项时，我无法循环浏览数据。它不是通过所有记录并显示它们，而是仅通过一组数据。它假设显示每个学生和他们参与的每个问题的详细信息。但它只显示一个学生和一个问题，这就是全部。

以下是它应显示的内容：

enter image description here

但目前只是展示了这个：

enter image description here

我相信造成这个问题的原因是我设置的动态WHERE子句。下面是动态WHERE子句的工作原理：

  • q.SessionId = ?
    • 的强制WHERE条件
  • 如果用户从学生下拉菜单中选择单个学生，则将AND sa.StudentId = ?添加到WHERE子句
  • 如果用户从学生下拉菜单中选择All学生选项，则从WHERE子句中删除或不显示AND sa.StudentId = ?
  • 如果用户从问题下拉菜单中选择单个问题，则将AND q.QuestionId = ?添加到WHERE子句
  • 如果用户从问题下拉菜单中选择All问题选项，则从WHERE子句中删除或不显示AND q.QuestionId = ?

我有三个下拉菜单（下面是样本数据的样子）：

会话 

<select name="session" id="sessionsDrop">
<option value="26">POKUB1</option>
<option value="27">POKUB2</option>
</select>

学生： 

<select name="student" id="studentsDrop">
<option value="0">All</option>
<option value="39">Luke Mcfadzen</option>
<option value="40">Chris Tucker</option>
</select>

问题： 

<select name="question" id="questionsDrop">
<option value="0">All</option>
<option value="72">1</option>
<option value="73">2</option>
</select>

不要忘记我在上面提到的WHERE条件是如何工作的。让我们说从会话下拉菜单中选择的会话是POKUB 1, drop down value: 26。

如果您选择单个学生和单个问题，则会正确显示详细信息，例如

  • 学生： Luke McFadzen - 下拉值：39
  • 问题： 1 - 下拉值：72

所以WHERE条件是q.SessionId = 26 AND sa.StudentId = 39 AND q.QuestionId = 72。

但是如果我在学生和问题下拉菜单中选择一个All选项，那么输出只会显示一个学生和一个问题，并且由于一些奇怪的原因，它结合了所有问题的答案并组合了所有学生回答单个输出的答案。

现在两个下拉菜单中的All选项的下拉值都为0，现在0不是从数据库中选择的值，但我们在动态where子句中声明了如果从特定下拉菜单中选择0值，则从WHERE子句中删除相关条件，例如：

  • All名学生和单个问题（价值72） - WHERE q.SessionId = 26 AND q.QuestionId = 72
  • 单身（价值39）学生和All个问题 - WHERE q.SessionId = 26 AND sa.StudentId = 39
  • All学生和All个问题 - WHERE q.SessionId = 26

上面的情景有问题

如果我只是使用静态WHERE子句WHERE q.SessionId = ?离开查询，那么如果我选择All学生和All问题，它会正确输出详细信息，但我需要查询才能工作从下拉菜单中选择所有不同的可能选项，因此我需要一个动态WHERE子句。如何让它工作，以便输出正确的细节？

代码：

    $selectedstudentanswerqry = "
        SELECT
        sa.StudentId, StudentAlias, StudentForename, StudentSurname, q.SessionId, 
        q.QuestionId, QuestionNo, QuestionContent, o.OptionType, q.NoofAnswers, 
        GROUP_CONCAT( DISTINCT Answer ORDER BY Answer SEPARATOR ',' ) AS Answer, r.ReplyType, QuestionMarks, 
        GROUP_CONCAT(DISTINCT StudentAnswer ORDER BY StudentAnswer SEPARATOR ',') AS StudentAnswer, ResponseTime, MouseClick, 
        (
        SELECT sum( StudentMark )
        FROM Student_Answer sta
        WHERE sa.StudentId = sta.StudentId
        AND sa.QuestionId = sta.QuestionId
        )StudentMark
        FROM Student st
        INNER JOIN Student_Answer sa ON (st.StudentId = sa.StudentId)
        INNER JOIN Student_Response sr ON (sa.StudentId = sr.StudentId) AND sa.QuestionId = sr.QuestionId
        INNER JOIN Question q ON (sa.QuestionId = q.QuestionId)
        INNER JOIN Answer an ON q.QuestionId = an.QuestionId
        LEFT JOIN Reply r ON q.ReplyId = r.ReplyId
        LEFT JOIN Option_Table o ON q.OptionId = o.OptionId
        ";

        // Initially empty
        $where = array('q.SessionId = ?');
        $parameters = array($_POST["session"]);
        $parameterTypes = 'i';


        //check if POST is empty

        // Check whether a specific student was selected
        $p_student = empty($_POST["student"])?'':$_POST["student"];

        switch($p_student){
        case 0:
            //dont' add where filters
            break;
        default:
            $where[] = 'sa.StudentId = ?';
            $parameters[] .= $_POST["student"];
            $parameterTypes .= 'i';
        }

        // Check whether a specific question was selected
        $p_question = empty($_POST["question"])?'':$_POST["question"];

        switch($p_question){
        case 0:
            //dont' add where filters
            break;
        default:
            $where[] = 'q.QuestionId = ?';
            $parameters[] .= $_POST["question"];
            $parameterTypes .= 'i';
        }

        // If we added to $where in any of the conditionals, we need a WHERE clause in
        // our query
        if(!empty($where)) {
            $selectedstudentanswerqry .= ' WHERE ' . implode(' AND ', $where);
            global $mysqli;
            $selectedstudentanswerstmt=$mysqli->prepare($selectedstudentanswerqry);
            // You only need to call bind_param once

            if (count($where) == 1) {
            $selectedstudentanswerstmt->bind_param($parameterTypes, $parameters[0]);
        }
        else if (count($where) == 2) {
            $selectedstudentanswerstmt->bind_param($parameterTypes, $parameters[0], $parameters[1]);
        }
        else if (count($where) == 3) {
            $selectedstudentanswerstmt->bind_param($parameterTypes, $parameters[0], $parameters[1], $parameters[2]);
        }

        }

        $selectedstudentanswerqry .= "
          GROUP BY sa.StudentId, q.QuestionId
          ORDER BY StudentAlias, q.SessionId, QuestionNo
        ";

    // get result and assign variables (prefix with db)
    $selectedstudentanswerstmt->execute(); 
    $selectedstudentanswerstmt->bind_result($detailsStudentId,$detailsStudentAlias,$detailsStudentForename,$detailsStudentSurname,$detailsSessionId,
    $detailsQuestionId,$detailsQuestionNo,$detailsQuestionContent,$detailsOptionType,$detailsNoofAnswers,$detailsAnswer,$detailsReplyType,$detailsQuestionMarks,
    $detailsStudentAnswer,$detailsResponseTime,$detailsMouseClick,$detailsStudentMark); 

    $selectedstudentanswerstmt->store_result();
    $selectedstudentanswernum = $selectedstudentanswerstmt->num_rows(); 

 while ($selectedstudentanswerstmt->fetch()) {

                //Check if the student data exist.
                if (!isset($questions[$detailsStudentId])) {
                    $questions[$detailsStudentId] = array(
                        'studentalias' => $detailsStudentAlias,
                        'studentforename' => $detailsStudentForename,
                        'studentsurname' => $detailsStudentSurname,
                        'questions' => array()
                    );
                }

                $questions[$detailsStudentId]['questions'][$detailsQuestionId] = array(
                    'questionno'=>$detailsQuestionNo,
                    'content'=>$detailsQuestionContent,
                    'optiontype'=>$detailsOptionType,
                    'noofanswers'=>$detailsNoofAnswers,
                    'answer'=>$detailsAnswer,
                    'replytype'=>$detailsReplyType,
                    'questionmarks'=>$detailsQuestionMarks,
                    'studentanswer'=>$detailsStudentAnswer,
                    'responsetime'=>$detailsResponseTime,
                    'mouseclick'=>$detailsMouseClick,
                    'studentmark'=>$detailsStudentMark
                );
            }

            $selectedstudentanswerstmt->close();

    foreach ($questions as $studentId => $studentData) {
        echo '<p>'.$studentData['studentalias'].' - '.$studentData['studentforename'].' '.$studentData['studentsurname'].'</p>';

        foreach ($studentData['questions'] as $questionId => $questionData) {
            echo '<p><strong>'.$questionData['questionno'].': '.$questionData['content'].'<br/>';
            echo $questionData['optiontype'].' - '.$questionData['noofanswers'].' - '.$questionData['answer'].' - '.$questionData['replytype'].' - '.$questionData['questionmarks'].'<br/>';
            echo $questionData['studentanswer'].' - '.$questionData['responsetime'].' - '.$questionData['mouseclick'].' - '.$questionData['studentmark'].'</strong></p>';
        }
    }

以下是$_POST['student']和$_POST['question']的可能var_dumps：

单身学生和单一问题：

  • 学生：Chris Tucker - 字符串（2）“40”
  • 问题：1 - 字符串（2）“72”

单身学生和所有问题：

  • 学生：Chris Tucker - 字符串（2）“40”
  • 问题：全部 - 字符串（1）“0”

所有学生和单个问题：

  • 学生：全部 - 字符串（1）“0”
  • 问题：1 - 字符串（1）“72”

所有学生和所有问题：

  • 学生：全部 - 字符串（1）“0”
  • 问题：全部 - 字符串（1）“0”

如果我选择var_dump($questions);个学生和All个问题，则下面是示例All：

array(1) { 
[39]=> array(4) { 
["studentalias"]=> string(8) "u4838229" 
["studentforename"]=> string(5) "Chris" 
["studentsurname"]=> string(6) "Tucker" 
["questions"]=> array(1) { 
[72]=> array(11) { 
["questionno"]=> int(1) 
["content"]=> string(14) "What is a RAM?" 
["optiontype"]=> string(3) "A-E" 
["noofanswers"]=> int(1) 
["answer"]=> string(7) "B,C,D,E" 
["replytype"]=> string(6) "Single" 
["questionmarks"]=> int(5) 
["studentanswer"]=> string(9) "A,B,C,D,E" 
["responsetime"]=> string(8) "00:00:07" 
["mouseclick"]=> int(1) 
["studentmark"]=> string(1) "2" } } } }

更新

如果我在仅检查q.SessionId = ?时使用静态WHERE子句保留mysqli查询，那么当我在etiher或两个下拉菜单中选择All选项时，它会输出结果很好没问题，只有我需要包含的动态where子句作为用户我能够选择一个单独的学生和/或All选项不能正常工作的个人问题。下面是使用静态WHERE子句时的mysqli代码：

$selectedstudentanswerqry = "
    SELECT
    sa.StudentId, StudentAlias, StudentForename, StudentSurname, q.SessionId, 
    q.QuestionId, QuestionNo, QuestionContent, o.OptionType, q.NoofAnswers, 
    GROUP_CONCAT( DISTINCT Answer ORDER BY Answer SEPARATOR ',' ) AS Answer, r.ReplyType, QuestionMarks, 
    GROUP_CONCAT(DISTINCT StudentAnswer ORDER BY StudentAnswer SEPARATOR ',') AS StudentAnswer, ResponseTime, MouseClick, 
    (
    SELECT sum( StudentMark )
    FROM Student_Answer sta
    WHERE sa.StudentId = sta.StudentId
    AND sa.QuestionId = sta.QuestionId
    )StudentMark
    FROM Student st
    INNER JOIN Student_Answer sa ON (st.StudentId = sa.StudentId)
    INNER JOIN Student_Response sr ON (sa.StudentId = sr.StudentId) AND sa.QuestionId = sr.QuestionId
    INNER JOIN Question q ON (sa.QuestionId = q.QuestionId)
    INNER JOIN Answer an ON q.QuestionId = an.QuestionId
    LEFT JOIN Reply r ON q.ReplyId = r.ReplyId
    LEFT JOIN Option_Table o ON q.OptionId = o.OptionId
    LEFT JOIN Session_Taken sta ON (st.StudentId = sta.StudentId)
      WHERE q.SessionId = ?
      GROUP BY sa.StudentId, q.QuestionId
      ORDER BY StudentAlias, q.SessionId, QuestionNo
    ";
    global $mysqli;
$selectedstudentanswerstmt=$mysqli->prepare($selectedstudentanswerqry);
$selectedstudentanswerstmt->bind_param('i',$_POST['session']);
// get result and assign variables (prefix with db)
$selectedstudentanswerstmt->execute(); 
$selectedstudentanswerstmt->bind_result($detailsStudentId,$detailsStudentAlias,$detailsStudentForename,$detailsStudentSurname,$detailsSessionId,
$detailsQuestionId,$detailsQuestionNo,$detailsQuestionContent,$detailsOptionType,$detailsNoofAnswers,$detailsAnswer,$detailsReplyType,$detailsQuestionMarks,
$detailsStudentAnswer,$detailsResponseTime,$detailsMouseClick,$detailsStudentMark);

3 个答案:

答案 0 :(得分：1)

我相信你问题的根源是：

    // Check whether a specific student was selected
    $p_student = empty($_POST["student"])?'':$_POST["student"];

    switch($p_student){
    case 0:
        //dont' add where filters
        break;
    default:
        $where[] = 'sa.StudentId = ?';
        $parameters[] .= $_POST["student"];
        $parameterTypes .= 'i';
    }

将学生添加到where子句的代码只执行一次，并且不支持多个学生被选中。

这样的事情应该有用，假设您修改代码以从表单传递学生ID数组：

if (!empty($_POST['student'])) {

    $students = filter_input_array(INPUT_POST, 'student', FILTER_SANITIZE_NUMBER_INT);

    if ($students !== false) {
        $num_students = count($students);
        $where[]      = 'sa.StudentId IN (' . rtrim(str_repeat('?,', $num_students), ',') . ')';
        $parameters   = array_merge($parameters, $students);
    }
}

一些事情：

  • 永远不要相信未经过清理的数据，在使用之前始终要清理/过滤。
  • 如果您将[]添加到表单字段的名称（即：<select name="student[]"> PHP会将其解释为$ _POST中的数组。
  • 这会使您的SQL查询返回多个结果，这意味着$questions将保留所有这些结果。

答案 1 :(得分：1)

empty（）将'0'视为空http://php.net/manual/en/function.empty.php， 所以在$p_student = empty($_POST["student"])?'':$_POST["student"]; $ p_student是真的，当$ _POST [“student”]为'0'时...结果，下面的情况总是'默认'，所以你应该将$ p_student设置为'' 0'如果为空（）它应该没问题......我想...（这当然是$ p_student和$ p_question ......）。 `

    $p_student = empty($_POST["student"])?0:$_POST["student"];  // Now if $_POST['student'] is either 0 or empty $p_student will be 0

    switch($p_student){
    case 0:
        //dont' add where filters
        break;
    default:
        $where[] = 'sa.StudentId = ?';
        $parameters[] .= $_POST["student"];
        $parameterTypes .= 'i';
    }

    // Check whether a specific question was selected
    $p_question = empty($_POST["question"])?0:$_POST["question"]; // Same here, if $_POST['question'] is either 0 or empty $p_question will be 0
    switch($p_question){
    case 0:
        //dont' add where filters
        break;
    default:
        $where[] = 'q.QuestionId = ?';
        $parameters[] .= $_POST["question"];
        $parameterTypes .= 'i';
    }`

答案 2 :(得分：0)

我认为你错过了

之后的结束} 
// You only need to call bind_param once

现在你的

if(!empty($where)) {

不会以它应该结束的地方结束......

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