PHP PDO::FETCH_ASSOC returns false

In this code fetch(PDO::FETCH_ASSOC) retunrs false even if $row>0.
I couldn’t find why this is happening.

Here session is not set as $member is null.

<?php 

$sql = "SELECT * FROM members WHERE username=:decrypted_login and password=:decrypted_pass";

$result = $dbh->prepare($sql);
$result->bindParam(':decrypted_login', $decrypted_login);
$result->bindParam(':decrypted_pass', $decrypted_pass);
$result->execute();
$rows = $result->fetch(PDO::FETCH_NUM);

if($rows > 0)
{
  $member = $result->fetch(PDO::FETCH_ASSOC);
  session_regenerate_id();
  $_SESSION['SESS_MEMBER_ID'] = $member['member_id'];
  $_SESSION['SESS_PASSWORD'] = $member['password'];
  $_SESSION['SESS_FIRST_NAME'] = $member['firstname'];
  session_write_close();
}

?>

I’ve read many and stackoverflow questions and forums but couldn’t find a solution for this.

var_dump($row); // gives an array   

var_dump($member) //shows bool(false).  

Answer

You are using fetch instead of rowCount:

$rows = $result->rowCount();

From PDO::fetch():

Fetches the next row from a result set.

The return value of this function on success depends on the fetch type. In all cases, FALSE is returned on failure.

I’d assume here that only 1 user can exist in the database with those credentials, when you first execute the $rows = $result->fetch(PDO::FETCH_NUM);, the resultset cursor is moved over to the next row-set (which doesn’t exist, as there was only a single row).

Therefore, you get a false in the later call.