SQL行foreach multiplation

Question

在此表上使用

 [         POSTS         ]
  | id |   title  | class |
  |----|----------|-------|
  | 1  |   4567   |    2  |
  | 2  |   1234   |    1  |
  | 3  |   9124   |    1  |
  | 3  |   9124   |    3  |
  ________________________

此代码

    $statment= $conn->prepare("SELECT * FROM Posts WHERE id = :id AND class in (1,2,3) ORDER BY class ASC");
$statment->execute([':id' => $id]);


  $classes = array();
  while($row = $statment->fetch()){
  if(!isset($classes[$row['class']])){ $classes[$row['class']] = array(); }
  $classes[$row['class']][] = $row['title'];
}


    foreach($classes as $key => $class){
   echo "Class Value: ".$key;
   foreach($class as $title){ echo "<a>".$title."</a>"; }

}

当我输入foreach代码时，每个值都会获得$ key，但echo "Class Value: ".$key;应该出现一次，然后显示$key的所有值，但是相反，$ key乘以＆amp;当具有例如class = 1的类超过3时，Everything开始中断。

原来是

$key:
ROW VALUE 1
ROW VALUE 1
ROW VALUE 1

会发生什么

$key:
ROW VALUE 1 [id = 1]
$key:
ROW VALUE 1 [id = 2]
$key:
ROW VALUE 1 [id = 3]

当有超过3行且值为1

时

$key:
ROW VALUE 1 [id = 1]
$key:
ROW VALUE 1 [id = 1]
$key:
ROW VALUE 1 [id = 2]
$key:
ROW VALUE 1 [id = 3]

此代码是我在此处提出的上一个问题的答案 https://stackoverflow.com/a/43054136/7490349