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[英]PHP/MySQLi - looping through an array to build dynamic WHERE clause
[英]How to create a mysqli dynamic WHERE clause
我这里有一个应用程序: 应用程序
该应用程序在那里向您展示了两个我想用作过滤器的下拉菜单,以便能够从相应的下拉菜单中确定所选学生和所选问题的学生答案。
看到下拉菜单,在应用程序中选择一个Assessment
从Assessment
下拉菜单并提交,你会看到学生和问题下拉下方显示的菜单。
现在,我想做的是根据用户单击“ Get Student Answers
按钮时从学生和问题下拉菜单中选择的选项来创建动态WHERE子句。
以下是当前查询。 查询必须具有默认子句SessionId = ?
始终在WHERE子句中。 其他子句studentId = ?
和questionId = ?
取决于用户从两个下拉菜单中选择的选项。
$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();
以下是学生和问题下拉菜单,作为示例html:
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>
我在想什么,如果选择了一个特定的学生然后包括StudentId = ?
在WHERE子句中,如果选择了特定的问题编号,则包括QuestionId = ?
在WHERE子句中。 但是,如果在“学生”下拉菜单中选择了“ All
值,则删除StudentId = ?
从WHERE子句中查找,因为我们正在寻找所有学生,而不是为特定学生而苦恼。 如果从“问题”下拉菜单中选择“ All
值”,但显然处理QuestionId = ?
则这是相同的QuestionId = ?
您知道您可以在此处编写子查询吗?
WHERE (SessionId = ?)
喜欢
WHERE SessionId IN(SELECT SessionId FROM ...)
http://dev.mysql.com/tech-resources/articles/subqueries_part_1.html
好吧,你知道吗? 我想我在这里误解了真正的问题。 您可能会发现它可以更好地工作:
$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
";
}
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