美好的一天。我有很多关系设置。我想知道如何对具有相同ID的行进行分组，并将其反映为与条目上的每个链接连接。
// from this // to this but with each link
----------Classes---------- ----------Classes----------
| Student Id | Lecture ID | | Student Id | Lecture ID |
| 1 | 1 | | 1 | 1; 2; 3 |
| 1 | 2 | | 1 | 4; 2 |
| 1 | 3 | ---------------------------
| 2 | 4 |
| 2 | 5 |
---------------------------
这是查询（没有组连接）：
$classes = "SELECT * FROM students, lectures, classes
WHERE students.student_id=classes.student_id
AND lectures.lecture_id=classes.lecture_id"
$class_result = mysqli_query($con, $classes);
while($class = mysqli_fetch_array($class_result){
echo '<table><tr>';
echo '<td><a href="student.php?id='.$class['student_id'].'">'.$class['student'].'</a></td>';
echo '<td><a href="lecture.php?id='.$class['lecture_id'].'">'.$class['lecture'].'</a></td>';
echo '</tr></table>';
}
----------Classes----------
| Student Id | Lecture ID |
| 1 | 1 |
| 1 | 2 |
| 1 | 3 |
| 2 | 4 |
| 2 | 5 |
---------------------------
这是查询（使用group concat）：
$classes = "SELECT students.student_id, student, lectures.lecture_id, GROUP_CONCAT(lecture SEPARATOR '; ')
FROM students, lectures, classes
WHERE students.student_id=classes.student_id
AND lectures.lecture_id=classes.lecture_id
GROUP BY student"
$class_result = mysqli_query($con, $classes);
while($class = mysqli_fetch_array($class_result){
echo '<table><tr>';
echo '<td><a href="student.php?id='.$class['student_id'].'">'.$class['student'].'</a></td>';
echo '<td><a href="lecture.php?id='.$class['lecture_id'].'">'.$class["GROUP_CONCAT(lecture SEPARATOR '; ')"].'</a></td>';
echo '</tr></table>';
}
----------Classes----------
| Student Id | Lecture ID | // this works but it cannot reflect each link of id of lecture
| 1 | 1; 2; 3 | // it only reflects link of one id for lecture
| 1 | 4; 2 |
---------------------------
这是实际的PHP部分：
<?php include ('connect.php'); ?>
<?php
$classes = "SELECT * FROM students, lectures, classes WHERE students.student_id=classes.student_id AND lectures.lecture_id=classes.lecture_id";
$class_result = mysqli_query($con, $classes);
?>
HTML / PHP部分：
<html>
<title>Classes</title>
<body>
<table border="1" cellspacing="0" cellpadding="10" width="500">
<tr>
<td colspan="2" align="right">
<a href="add_class.php">Add Class</a>
</td>
</tr>
<tr>
<th>Student</th>
<th>Lecture</th>
</tr>
<?php while($class = mysqli_fetch_array($class_result)) { ?>
<tr>
<td align="center"><a href="student.php?student_id=<?=$class['student_id']?>"><?=$class['student']?></a></td>
<td align="center"><a href="lecture.php?lecture_id=<?=$class['lecture_id']?>"><?=$class['lecture']?></a></td>
</tr>
<?php } ?>
</table>
</body>
</html>
<?php include('close.php')?>
这些是表格：
----------Classes---------- // wanted to ----------Classes----------
| Student | Lecture | be like | Student | Lecture |
| John | Math | this | | Math; |
| John | Literature | ---> | John | Literature;|
| Paul | Math | clickable | | Physics; |
| Paul | Speech | each | | Speech |
| Paul | Literature | lecture ---------------------------
| John | Physics | | | Math; |
| Paul | Physics | | Paul | Speech; |
| John | Speech | | | Literature;|
--------------------------- | | Physics |
---------------------------
答案 0 :(得分：0)
我可能会这样做：
$classes = "SELECT * FROM students, lectures, classes
WHERE students.student_id=classes.student_id
AND lectures.lecture_id=classes.lecture_id ORDER BY students.student_id";
$class_result = mysqli_query($con, $classes);
$student_ids = [];
while($class = mysqli_fetch_array($class_result)){
//fixed missing ) - while($class = mysqli_fetch_array($class_result){
if(!isset($student_ids[$class['student_id']])){
if(count($student_ids) > 1) echo '</tr></table>'; //close previous list
$student_ids[$class['student_id']] = true;
echo '<table><tr>';
echo '<td><a href="student.php?id='.$class['student_id'].'">'.$class['student'].'</a></td>';
}
echo '<td><a href="lecture.php?id='.$class['lecture_id'].'">'.$class['lecture'].'</a></td>';
}
if(count($student_ids) > 1) echo '</tr></table>'; //close last list
请注意Order By和$student_ids数组。这样你就会得到
等...
我建议使用说明列表：
<dl>
<dt>Student A</td>
<dd>Lecture 1</dd>
<dd>Lecture 2</dd>
</dl>
但是你必须要做一些CSS。对我来说，这似乎是一个更好的结构，因为它可以让你消除一些标签，并为学生链接提供不同的标签。但这取决于你。
在任何情况下，只要您拥有所需数据，HTML结构和“样式”就是一个小细节。更不用说根据问题中提供的信息，没有办法知道你希望它如何看待。
那就是说，演讲链接似乎独立于学生。在我看来它应该包括学生的东西或链接是不相关的。我的意思是什么区别。
学生A，第1讲
和
学生B，第1讲
两个讲座链接都是一样的。
答案 1 :(得分：0)
<?php
$conn=mysqli_connect("localhost","root","","database");
$student_query="SELECT student_id FROM classes";
$student_result=mysqli_query($conn,$student_query);
while($row_student=$student_result->fetch_assoc())
{
$student_id=$row_student['student_id'];
$lecturer_query="SELECT lecturer_id FROM classes where student_id='$$student_id'";
$lecturer_result=mysqli_query($conn,$lecturer_query);
while($row_lecturer=$lecturer_result->fetch_assoc())
{
$lecturer_id[]=$row_lecturer['lecturer_id'];
}
$result[]=array('student_id'=>$student_id,'lecturer_id'=>$lecturer_id);
}
echo json_encode($result);
答案 2 :(得分：0)
最后经过所有的搜索和提取想法。我终于成功完成了这项工作。这就是代码的用法。
<?php
$classes = "SELECT * FROM students, lectures, classes WHERE students.student_id=classes.student_id AND lectures.lecture_id=classes.lecture_id GROUP BY students.student_id";
$class_result = mysqli_query($con, $classes);
while($class = mysqli_fetch_array($class_result)) {
$student_id = $class['student_id'];
$lectures = mysqli_query($con,"SELECT * FROM students, lectures, classes WHERE students.student_id=classes.student_id AND lectures.lecture_id=classes.lecture_id AND students.student_id='$student_id'");
$counter = 0;
?>
<tr>
<td align="center"><a href="student.php?student_id=<?=$class['student_id']?>"><?=$class['student']?></a></td>
<td align="center">
<?php while($lecture = mysqli_fetch_array($lectures)) { ?>
<a href="lecture.php?lecture_id=<?=$lecture['lecture_id']?>"><?=$lecture['lecture'];?></a>
<?php } ?>
</td>
</tr>
<?php } ?>
现在表格如下：
-----------------------Classes----------------------------
| Student | Lectures |
----------------------------------------------------------
| John | Math Literature Physics Speech |
----------------------------------------------------------
| Paul | Math Speech Literature Physics |
----------------------------------------------------------
现在我将处理讲座的分隔符/分隔符。 （例如数学;文学;物理;演讲）。谢谢你的帮助。