<?php

/* Array having the days as keys (YYYY-mm-dd) and the view count as values */
$days = array();

/* Initialize the days keys to 0 */
for ($i = 0; $i < 7; $i++)
{
    $dayUts = mktime(0, 0, 0, date('n'), date('j') - $i, date('Y'));
    $day = date('Y-m-d', $dayUts);
    $days[$day] = 0;
}

/* Now read the view count from the DB */
$query = 'SELECT DATE_FORMAT(view_count_date, "%Y-%m-%d") AS time, count(*) AS view_count from ads_view_count WHERE view_count_date >= (NOW() - INTERVAL 7 DAY) AND view_count_user_id = :id';

/* Note: be sure to validate $_SESSION['id'] */
$res = $pdo->prepare($query);
$res->bindValue(':id', $_SESSION['id'], PDO::PARAM_INT);
$res->execute();

/* Now we update the $days array with the view count from the query */
while ($row = $res->fetch(PDO::FETCH_ASSOC))
{
    if (array_key_exists($row['time'], $days))
    {
        $days[$row['time']] = intval($row['view_count'], 10);
    }
}