php - Infinite Loop with While inside Foreach and MySQL

Question

I'm having a very odd problem with PHP/MySQL...

echos "id;id"

 foreach($ids as $id) {
      echo "id;";
 }

echos "id;id;id;id;..." (infinite loop)

 foreach($ids as $id) {
      while($row = mysqli_fetch_array(mysqli_query($conn, "SELECT * FROM `Table` WHERE `id`=$id;") {
           echo "id;";
      }
 }

The reason I have a foreach() statement is because I have $ids sorted.

Answer 1

您将获得一个无限循环，这仅仅是因为您每次通过while循环都重新运行查询。这意味着，对于每个$id，您不断运行查询并从中提取第一行。因此，对于返回多于零行的任何查询，该查询的持续重新执行将使while循环无限循环。

它在功能上类似于下面的伪代码，它也将永远循环，因为您正在修改循环中的控制条件：

loop i from 1 to 10
    set i to 1
endloop

您应该尝试以下方法：

foreach($ids as $id) {
    $result = mysqli_query($conn, "SELECT * FROM `Table` WHERE `id`=$id;");
    while($row = mysqli_fetch_array($result)) {
       echo "id;";
    }
}

这将为每个 ID运行一次while查询，循环将处理该查询的行。