试图建立一个动态的，其中使用mysqli的条款时，我得到了不少错误：
警告：参数2 mysqli_stmt :: bind_param（）预计为参考，值...给出线319
警告：mysqli_stmt ::执行（）：（HY000 / 2031）：在没有准备好的声明中...为参数提供在线328数据
警告：mysqli_stmt :: bind_result（）：（HY000 / 2031）：在没有准备好的声明中...为参数提供在线331数据
警告：mysqli_stmt :: store_result（）：（HY000 / 2014）：命令不同步; 你现在不能在...上线332运行此命令
即时猜测有是需要解决的问题，但发生的事情是，如果这两个中的一个下拉菜单的不等于变化不大All或者如果双方不等于All ，然后将其与错误的出现。
下面是代码显示两个下拉菜单和所述查询（具有动态where子句）随后根据选择N个选项：
HTML：
学生下拉菜单：
<select name="student" id="studentsDrop">
<option value="All">All</option>
<option value="11">John May</option>
<option value="23">Chris Park</option>
</select>
问题编号下拉菜单
<select name="question" id="questionsDrop">
<option value="All">All</option>
<option value="123">1</option>
<option value="124">2</option>
<option value="125">3</option>
</select>
PHP /库MySQLi：
function StudentAnswers()
{
/*BELOW IS THE QUERY WHERE I AM TRYING TO RETRIEVE DATA DEPENDING ON THE ASSESSMENT CHOSEN AND
THEN DEPENDING ON OPTIONS CHOSEN IN STUDENT AND QUESTION NUMBER DROP DOWN MENU */
$selectedstudentanswerqry = "
SELECT
StudentAlias, StudentForename, StudentSurname, q.SessionId, 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, StudentMark
FROM Student s
INNER JOIN Student_Answer sa ON (s.StudentId = sa.StudentId)
INNER JOIN Student_Response sr ON (sa.StudentId = sr.StudentId)
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"]);
$parameterTypes = 'i';
// Check whether a specific student was selected
if($_POST["student"] !== 'All') {
$where[] = 'sa.StudentId = ?';
$parameters[] =& $_POST["student"];
$parameterTypes .= 'i';
}
// Check whether a specific question was selected
// NB: This is not an else if!
if($_POST["question"] !== 'All') {
$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($selectedstudentanswerqry);
// You only need to call bind_param once
call_user_func_array(array($selectedstudentanswerstmt, 'bind_param'),
array_merge(array($parameterTypes), $parameters)); //LINE 319 ERROR 1
}
//Add group by and order by clause to query
$selectedstudentanswerqry .= "
GROUP BY sa.StudentId, q.QuestionId
ORDER BY StudentAlias, q.SessionId, QuestionNo
";
// get result and assign variables (prefix with db)
$selectedstudentanswerstmt->execute(); //LINE 328 ERROR 2
//bind database fields
$selectedstudentanswerstmt->bind_result($detailsStudentAlias,$detailsStudentForename,$detailsStudentSurname,$detailsSessionId,$detailsQuestionNo,
$detailsQuestonContent,$detailsOptionType,$detailsNoofAnswers,$detailsAnswer,$detailsReplyType,$detailsQuestionMarks,$detailsStudentAnswer,$detailsResponseTime,
$detailsMouseClick,$detailsStudentMark); //LINE 331 ERROR 3
//store results retrieved
$selectedstudentanswerstmt->store_result(); //LINE 332 ERROR 4
//count number of rows retrieved
$selectedstudentanswernum = $selectedstudentanswerstmt->num_rows();
//output query
echo "$selectedstudentanswerqry";
}
?>
这里是一个演示： DEMO
在演示中选择从下拉菜单并提交评估。 你会看到两个下拉菜单。 让他们都设置为All并提交，它将输出查询，没有任何问题。 没有在下拉菜单中的一个，改变All到一个特定的学生或问题，然后提交。 现在你会看到错误
如何转储：
所述的结果var_dump(array_merge(array($parameterTypes), $parameters))); 当我和值选择会话（评估） 31 ，学号值40 ，和题号值81 ，和WHERE子句WHERE q.SessionId = ? AND sa.StudentId = ? AND q.QuestionId = ? WHERE q.SessionId = ? AND sa.StudentId = ? AND q.QuestionId = ? ：
我正在此输出： array(4) { [0]=> string(3) "iii" [1]=> string(2) "31" [2]=> string(2) "40" [3]=> string(2) "81" }
