<?php

/* Array having the MONTHS as keys (numeric month, from 1 to 12) and the view count as values */
$months = array();

/* Initialize the days keys to 0, for both ads and phone */
for ($i = 0; $i < 12; $i++)
{
    $monthUts = mktime(0, 0, 0, date('n') - $i, 1, date('Y'));
    $month = intval(date('m', $monthUts), 10);
    $months[$month] = array('ads' => 0, 'phone' => 0);
}

/* Now read the view count from the DB. I take the last 12 months. */
$query = 'SELECT DATE_FORMAT(view_count_date, "%m") AS time, count(*) AS view_count_ads, -1 AS view_count_phone FROM ads_view_count WHERE view_count_date >= (NOW() - INTERVAL 12 MONTH) AND view_count_user_id = :id GROUP BY DATE_FORMAT(view_count_date, "%m") UNION SELECT DATE_FORMAT(view_count_date, "%m") AS time, -1 AS view_count_ads, count(*) AS view_count_phone FROM phone_view_count WHERE view_count_date >= (NOW() - INTERVAL 12 MONTH) AND view_count_user_id = :id GROUP BY DATE_FORMAT(view_count_date, "%m")';

/* 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 $months array with the view count from the query */
while ($row = $res->fetch(PDO::FETCH_ASSOC))
{
    $row_month = intval($row['time'], 10);
    $ads_count = intval($row['view_count_ads'], 10);
    $phone_count = intval($row['view_count_phone'], 10);

    /* If view_count_ads is -1 it means this is a result from phone_vew_count */
    if (ads_count  == -1)
    {
        $months[$row_month]['phone'] = $phone_count;
    }
    else /* Otherwise, it's a result from ads_vew_count */
    {
        $months[$row_month]['ads'] = $ads_count;
    }
}