How to find user id by username in PHP PDO mySQL?

Question

Hello guys i am trying to get user id by username using PDO and mySQL... My codes are:

<?php
if(isset($_POST['log']))
{
    $logname = @$_POST["logname"];
$logpass = @$_POST["logpass"]; 

$sql = "SELECT username, password FROM users WHERE username=? AND 
  password=? ";
    $query = $conn->prepare($sql);
    $query->execute(array($logname,$logpass));
    if($query->rowCount() >= 1) {
        $_SESSION["activeuser"] = true;
    $_SESSION ["username"] = $logname;


//here is starting my problem
    $findid = $conn->prepare("SELECT id FROM users WHERE username= :username"); 
    $findid->bindParam(':username', $logname);
    $findid->execute();
    $_SESSION ["userid"] = $findid;

    header("Location:index.php");
        }
        else {echo "incorrect username or password";}
}?>

This is my login.php, evrything is working good until $findid... I am trying to bind $_SESSION["userid"] = //The id of user selected from database..

if you have any other ideas you can share thank you for reading :)

Edit: The problem is solved thanks for " Eric Lam " .. Just after $findid->execute();I edited $_SESSION ["userid"] = $findid; to->

$result = $findid->fetch();
$_SESSION ["userid"] = $result[0]; :) :) 

Answer 1

PDO::Prepare returns a PDOStatement. you cannot assign a PDOStatement to the Session.
You need to bind the results to a variable.

Try

$findid->execute();
$result = $findid->fetch();
$_SESSION ["userid"] = $result[0];