Php 如何计算所有在场学生的百分比
有两张桌子将一起工作 第一表：Php 如何计算所有在场学生的百分比,php,mysql,Php,Mysql,有两张桌子将一起工作 第一表： AttendanceID TeacherID BatchID SubjectID SemesterID Date 32 110 8 9 1 2016-08-04 31 102 8 10 1 2016-07-17 30 108 6 22
AttendanceID TeacherID BatchID SubjectID SemesterID Date
32 110 8 9 1 2016-08-04
31 102 8 10 1 2016-07-17
30 108 6 22 3 2016-06-27
29 109 7 18 2 2016-06-27
28 109 8 13 1 2016-06-27
27 110 7 7 2 2016-06-27
26 110 8 9 1 2016-06-27
25 104 2 42 7 2016-04-20
24 104 5 35 5 2016-04-14
23 104 2 42 7 2016-04-14
22 102 2 41 7 2016-04-13
21 102 2 41 7 2016-04-10
20 102 6 23 3 2016-04-10
19 102 6 23 3 2016-04-10
AttendanceID21科目的第二个表中所有学生的百分比，总人数可以通过第一个表AttendanceID
我在PHP中所做的是：首先，我通过以下查询从第一个表中获取总数：
SELECT COUNT(AttendanceID) FROM attendances WHERE SubjectID = ? AND BatchID = ?"
一旦我从第一个表中获得特定主题和批次的总出勤人数，我将其存储在变量$total
中，然后我编写另一个查询以从第二个表中获得出勤人数：
SELECT COUNT(AttendanceDetailID) FROM attendancedetail WHERE CollegeID = ? AND Status = 'present' AND SubjectID = ?"
获得获得的出勤率后，我将其存储在变量$acquired
一旦我得到这两个值，我就用PHP计算百分比，如下所示：
if(!empty($total) && !empty($obtained)) {
$result = (($obtained * 100)/ $total);
$result = round($result);
}
以下是PHP的完整代码：
public function showStateOfAttendance($subjectID, $batchID){
$st = $this->conn->prepare("SELECT CollegeID, Name, Gender, Photo FROM students WHERE BatchID = ?");
$st->bind_param("i", $batchID);
$st->execute();
$st->store_result();
$num_rows = $st->num_rows;
$st->bind_result($college_id, $name, $gender, $photo);
$this->response['attendance'] = array();
while($st->fetch()) {
$this->calcultaionOfAttendance($subjectID, $college_id, $name, $gender, $photo, $batchID);
}
return json_encode($this->response);
$st->free_result();
$st->close();
}
public function calcultaionOfAttendance($subjectID, $studentID, $name, $gender, $photo, $batchID) {
$stmt = $this->conn->prepare("SELECT COUNT(AttendanceID) FROM attendances WHERE SubjectID = ? AND BatchID = ?");
$stmt->bind_param("ii", $subjectID, $batchID);
$stmt->execute();
$stmt->store_result();
$num_rows = $stmt->num_rows;
$stmt->bind_result($AttendanceID);
while($stmt->fetch()) {
$total = $AttendanceID;
}
$stmt->free_result();
$stmt->close();
$stmt2 = $this->conn->prepare("SELECT COUNT(AttendanceDetailID) FROM attendancedetail WHERE CollegeID = ? AND Status = 'present' AND SubjectID = ?");
$stmt2->bind_param("ii", $studentID, $subjectID);
$stmt2->execute();
$stmt2->store_result();
$stmt2->bind_result($AttendanceDetailID);
while($stmt2->fetch()){
$obtained = $AttendanceDetailID;
}
if(!empty($total) && !empty($obtained)) {
$result = (($obtained * 100)/ $total);
$result = round($result);
$rating = ($result)/20;
$tmp = array();
$tmp['result'] = $result;
$tmp['total'] = $total;
$tmp['obtained'] = $obtained;
$tmp['rating'] = $rating;
$tmp['name'] = $name;
$tmp['college_id'] = $studentID;
$tmp['gender'] = $gender;
$tmp['photo'] = $photo;
array_push($this->response['attendance'],$tmp);
//var_dump(array($total, $obtained, $result, $rating, $studentID, $name));
}else if(empty($total)) {
$tmp = array();
$tmp['result'] = 0.0;
$tmp['total'] = 0.0;
$tmp['obtained'] = $obtained;
$tmp['rating'] = 0.0;
$tmp['name'] = $name;
$tmp['college_id'] = $studentID;
array_push($this->response['attendance'],$tmp);
//var_dump(array("0.0",$obtained, "0.0","0.0",$studentID,$name));
}else if(empty($obtained)) {
$tmp = array();
$tmp['result'] = 0.0;
$tmp['total'] = $total;
$tmp['obtained'] = 0.0;
$tmp['rating'] = 0.0;
$tmp['name'] = $name;
$tmp['college_id'] = $studentID;
array_push($this->response['attendance'],$tmp);
//var_dump(array($total, "0.0", "0.0","0.0", $studentID , $name));
}
}
下面是我所做查询的android屏幕截图：以下是SubjectID=23
和BatchID=6
它可以让我得到所需的结果，但我需要更好的方法来计算它，是否可以用单个查询来实现这一点
谢谢
将查询放入子选择中：
SELECT
(SELECT COUNT(AttendanceDetailID) FROM attendancedetail WHERE CollegeID = ? AND Status = 'present' AND SubjectID = ?)
/ (SELECT COUNT(AttendanceID) FROM attendances WHERE SubjectID = ? AND BatchID = ?)
* 100
或（更可读）连接两个子查询：
SELECT (obtained * 100) / total
FROM (
SELECT COUNT(AttendanceDetailID) AS total
FROM attendancedetail
WHERE CollegeID = ? AND Status = 'present' AND SubjectID = ?
) t
CROSS JOIN (
SELECT COUNT(AttendanceID) AS obtained
FROM attendances
WHERE SubjectID = ? AND BatchID = ?
) a
将查询放入子选择中：
SELECT
(SELECT COUNT(AttendanceDetailID) FROM attendancedetail WHERE CollegeID = ? AND Status = 'present' AND SubjectID = ?)
/ (SELECT COUNT(AttendanceID) FROM attendances WHERE SubjectID = ? AND BatchID = ?)
* 100
或（更可读）连接两个子查询：
SELECT (obtained * 100) / total
FROM (
SELECT COUNT(AttendanceDetailID) AS total
FROM attendancedetail
WHERE CollegeID = ? AND Status = 'present' AND SubjectID = ?
) t
CROSS JOIN (
SELECT COUNT(AttendanceID) AS obtained
FROM attendances
WHERE SubjectID = ? AND BatchID = ?
) a
根据您的示例，您甚至不需要访问第一个表。你可以直接从第二行的数据计算出来
根据您的示例，您甚至不需要访问第一个表。您可以直接从第二行中的数据计算出来。试试：
SELECT s.CollectID, s.Name, s.Gender, s.Photo,
(SELECT count(AttendanceID) from attendances WHERE SubjectID =? and BatchID = s.BatchID) as total,
(SELECT count(AttendanceDetailID) FROM attendancedetail WHERE CollegeID = s.CollectID and Status = 'present' and SubjectID = ?) as obtained
FROM students s
WHERE s.BatchID = ?
尝试：
嗨，它工作得很好，但它只给了我一个学生的计算。如何从where子句中计算特定批次和科目的每个学生Remove和CollegeID=1214
，我想我试过了，但它只计算了这个学生的ID:1212，结果是：presentCount\Uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu这个学生：1212即使我删除了和CollegeID=1214
，你也需要给我看你调用这个查询的代码。你可以编辑你的问题我正在PHPMyAdmin MySqlHi中执行你的查询它工作得很好，但是它只给了我一个学生的计算。如何从where子句中计算特定批次和科目的每个学生Remove和CollegeID=1214
，我想我试过了，但它只计算了这个学生的ID:1212，结果是：presentCount\Uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu这个学生：1212即使我删除了和CollegeID=1214
，你也需要给我看你调用这个查询的代码。您可以编辑您的问题我正在PHPMyAdmin MySqlits中执行您的查询在PHPMyAdmin Mysql中给我这个错误：每个派生表都必须有自己的别名它只显示一行，而不是所有学生。请告诉我一些让每个学生计算特定主题和批次的方法，记住AttendanceID
It在PhpMyAdmin Mysql中给我这个错误：每个派生表都必须有自己的别名它只显示一行，而不是所有学生。请告诉我一些让每个学生计算特定主题和批次的方法，记住AttendanceID
fyi的计数，函数参数名称上的开关a-roo$这->计算持久性（$subjectID、$college\u id、$name、$gender、$photo、$batchID）；和公共函数calcultaionOfAttendance（$subjectID、$studentID、$name、$gender、$photo、$batchID）{对不起，我不明白，你能详细说明一下吗？只是通过跟踪你的函数来尝试看看它在做什么；你传入了$college\u id，但计算Fattendance将其引用为$studentID；它可能会增加一些混乱，但没有什么大的。好的，谢谢你，我肯定会更改它：）仅供参考，函数参数na上的开关a-roome.$this->calcultaionOfAttendance（$subjectID、$college\u id、$name、$gender、$photo、$batchID）和公共函数calcultaionOfAttendance（$subjectID、$studentID、$name、$gender、$photo、$batchID）{对不起，我不明白，你能详细说明一下吗？只是通过跟踪你的函数来尝试看看它在做什么；你输入了$college\u id，但计算Fattendance将其引用为$studentID；它可能会增加一些混乱，但没有什么大的。好的，谢谢你，我肯定会更改它：）它工作了！谢谢分配。请向我推荐place，我也可以学习这些复杂的查询。只要接触它，你就会学得很好。我在工作时总是写一页长的查询，呵呵。但是如果你的代码得到了正确的结果，你只需要做一些跟踪，看看它在做什么。太好了。你很惊讶你猜对了学生
表自我惊异。我想在FB或任何地方添加你作为朋友，因为我需要像你这样的人在我的大学项目中进行一些查询。请参见ShowStateofAttendance（）向我展示了学生表。太棒了。通过此sharoonamjid@gmail.com
每当我收到任何与查询相关的问题时，我都会将其发布在Stack Overflow中，并向您发送问题链接以帮助我解决问题。这很好吗？成功了！谢谢分配。请建议我可以学习这些复杂查询的地方。只需在工作中，我一直在写一页长的查询，呵呵。但是如果你的代码得到了正确的结果，你只需要做一些跟踪，看看它在做什么。太好了。你真了不起