我可以在PHP中有2个标头位置吗？

Question

So, I know my code was working and I have tried un-doing all steps to see where the bug is, but I am still keep getting an error

my php id=0.

Can you guys show me how I can fix my code up?

The error is as follows:

undefined variable list_id. It works on my localmachine but not when uploaded to server.

Thanks.

The following is my code:

if(!empty($_GET['id'])){
  $list_id = intval(($_GET['id']));
  try {
        $sql = 'SELECT * FROM items where id =' . $list_id;
        $query = $pdo->prepare($sql);
        $query->execute();
  } catch(Exception $e) {
        echo $e->getMessage();
        die();
  }
  $list = $query->fetch(PDO::FETCH_ASSOC);
  if ($list == FALSE) {

    header("location: index.php");
  } 


}

if ($list_id == 0) {
    header("location: index.php");
}

Answer 1

Seems there are a few issues here. I have added the comments inline.

if(!empty($_GET['id'])){
    $list_id = intval($_GET['id']); //was double parenthesis here
    try {
            $sql = 'SELECT * FROM items where id =' . $list_id;
            $query = $pdo->prepare($sql);
            $query->execute();
        } catch(Exception $e) {
            echo $e->getMessage();
            die();
        }
    $list = $query->fetch(PDO::FETCH_ASSOC);
    $count = count($list); //count result and use for comparison instead of false
    if ($count === 0) {
        header("location: index.php");
        exit;
    } 

} else {
    header("location: index.php"); //if no $_GET, redirect
    exit;
}