我这里有一个应用程序:应用程序
该应用程序向您显示我想用作过滤器的两个下拉菜单,以便能够从各自的下拉菜单中确定所选学生和所选问题的学生答案。
要查看下拉菜单,请在应用程序中从Assessment
下拉菜单中选择一个Assessment
并提交,您将看到下方显示的学生和问题下拉菜单。
现在我想做的是创建一个动态 WHERE 子句,具体取决于用户单击Get Student Answers
按钮时从学生和问题下拉菜单中选择的选项。
下面是当前查询。查询必须始终在 WHERE 子句中SessionId = ?
默认子句。其他子句studentId = ?
和questionId = ?
取决于用户的选项 已从两个下拉列表中选择。
$selectedstudentanswerqry = "
SELECT
StudentAlias, q.SessionId, QuestionNo, QuestionContent, o.OptionType, GROUP_CONCAT( DISTINCT Answer
ORDER BY Answer SEPARATOR ',' ) AS Answer, r.ReplyType,
GROUP_CONCAT(DISTINCT StudentAnswer ORDER BY StudentAnswer SEPARATOR ',') AS StudentAnswer, ResponseTime
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
WHERE (SessionId = ?)
GROUP BY sa.StudentId, q.QuestionId
ORDER BY StudentAlias, q.SessionId, QuestionNo
";
global $mysqli;
$selectedstudentanswerstmt=$mysqli->prepare($selectedstudentanswerqry);
// You only need to call bind_param once
$selectedstudentanswerstmt->bind_param("i",$_POST["session"]);
// get result and assign variables (prefix with db)
$selectedstudentanswerstmt->execute();
$selectedstudentanswerstmt->bind_result($detailsStudentAlias,$detailsSessionId,$detailsQuestionNo,
$detailsQuestonContent,$detailsOptionType,$detailsAnswer,$detailsReplyType,$detailsStudentAnswer,$detailsResponseTime);
$selectedstudentanswerstmt->store_result();
$selectedstudentanswernum = $selectedstudentanswerstmt->num_rows();
以下是作为示例 html 的学生和问题下拉菜单:
学生下拉菜单:
<select name="student" id="studentsDrop">
<option value="All">All</option>
<option value="3">u0499220 - Jack Briggs</option>
<option value="7">u0093220 - Mary Kay</option>
</form>
问题下拉菜单:
<select name="question" id="questionsDrop">
<option value="All">All</option>
<option value="34">1</option>
<option value="35">2</option>
<option value="36">3</option>
</form>
我在想这样的事情,如果选择了特定学生,然后在 WHERE 子句中包含StudentId = ?
,如果选择了特定问题编号,则在 WHERE 子句中包含QuestionId = ?
。但是,如果在学生下拉菜单中选择了All
值,则从 WHERE 子句中删除StudentId = ?
,因为我们正在寻找所有学生,而不是针对特定学生进行缩减。如果从"问题"下拉菜单中选择All
值,则情况相同,但显然要处理QuestionId = ?
你知道你可以在这里写一个子查询吗?
WHERE (SessionId = ?)
喜欢
WHERE SessionId IN(SELECT SessionId FROM ...)
http://dev.mysql.com/tech-resources/articles/subqueries_part_1.html
好的,你知道吗?我想我误解了这里真正的问题。您可能会发现这工作得更好:
$selectedstudentanswerqry = "
SELECT
StudentAlias, q.SessionId, QuestionNo, QuestionContent, o.OptionType, GROUP_CONCAT( DISTINCT Answer
ORDER BY Answer SEPARATOR ',' ) AS Answer, r.ReplyType,
GROUP_CONCAT(DISTINCT StudentAnswer ORDER BY StudentAnswer SEPARATOR ',') AS StudentAnswer, ResponseTime
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";
if (studentId = something && questionId = something) {
$selectedstudentanswerqry .= "WHERE (SessionId = ?)
GROUP BY sa.StudentId, q.QuestionId
ORDER BY StudentAlias, q.SessionId, QuestionNo
";
} else if (studentId = somethingelse && questionId = somethingelse) {
$selectedstudentanswerqry .= "WHERE (SessionId = ?)
GROUP BY sa.StudentId, q.QuestionId
ORDER BY StudentAlias, q.SessionId, QuestionNo
";
} else {
$selectedstudentanswerqry .= "WHERE (SessionId = ?)
GROUP BY sa.StudentId, q.QuestionId
ORDER BY StudentAlias, q.SessionId, QuestionNo
";
}