如何计算ID匹配的行？

Question

I'm currently having some difficulty with determining if any rows match a specific user id. The code runs fine, but the if statement (if($notifs !== false) always returns true and hence "No notifications found" never displays. How do I write the statement to only check for "receive_id" that match the current session id?

$user_id = $_SESSION['userID'];

if(isset($_POST["view"]))
{

$stmt = $user_notif->runQuery("SELECT * FROM tbl_users WHERE userID=:uid");
$stmt->execute(array(":uid"=>$user_id));
$row = $stmt->fetch(PDO::FETCH_ASSOC);

$stmt = $user_notif->runQuery("SELECT * FROM notif_follow WHERE receive_id= ? ORDER BY id DESC LIMIT 5");
$stmt->bindValue(1,$user_id);
$stmt->execute();
$notifs = $stmt->fetchAll(PDO::FETCH_ASSOC);

$notification = '';

if($notifs !== false)
 {
  foreach($notifs as $notif)
  {

  $send_id = $notif['send_id'];

  $query2 = $user_notif->runQuery("SELECT id FROM following WHERE user1_id=:uid1 AND user2_id=:uid2");
  $query2->execute(array(":uid1"=>$user_id,":uid2"=>$send_id));
  $query2result = $query2->fetch(PDO::FETCH_ASSOC);

  if($query2result !== false){
  $follow .= '<a href="followoff.php?id='.$send_id.'"><button class="button">Remove Channel</button></a>';
  }
  else{
  $follow .= '<a href="followon.php?id='.$send_id.'"><button class="button">Add Channel</button></a>';
  }

  $notification .= '
   <li>
     <div class="notifbox">
     <strong style="color: #4b8ed3;">'.$notif["send_name"].'</strong><p style="color: #fff;"> has added you.</p>

     '.$follow.'

&nbsp<a href="index.php?id='.$notif["send_id"].'"><button class="button">View Channel</button></a>
     </div>
   </li>
   <div class="sectionheader3"></div>
   ';

  }
 }
 else
 {
  $notification .= '<li><h2 style="color: #4b8ed3; padding: 10px;">No Notifications Found<h2></li>';
 }

Answer 1

http://php.net/manual/en/pdostatement.fetchall.php says:

An empty array is returned if there are zero results to fetch, or FALSE on failure.

A query that matches zero rows is not a failure. It's a success at giving you the information that there are zero matching rows.

So you shouldn't compare with $notifs !== false , which compares exactly to the boolean false . You might like to compare with:

if (!$notifs)

This will also test for the empty array.

Answer 2

fetchAll only returns false if the query failed, but it's not failing. The result is an array. Your best to check if count($notifs) > 0 and also if $notifs === false for the possibility of the query failing.

Answer 3

Try

if ($stmt->RowCount() > 0) {
$notifs = $stmt->fetchAll(PDO::FETCH_ASSOC);
//code here
}

Instead of

$notifs = $stmt->fetchAll(PDO::FETCH_ASSOC);
if($notifs !== false) {
//code here
}