FressRSS/app/Models/StatsDAOSQLite.php

<?php

class FreshRSS_StatsDAOSQLite extends FreshRSS_StatsDAO {

	protected function calculateEntryRepartitionPerFeedPerPeriod($period, $feed = null) {
		if ($feed) {
			$restrict = "WHERE e.id_feed = {$feed}";
		} else {
			$restrict = '';
		}
		$sql = <<<SQL
SELECT strftime('{$period}', e.date, 'unixepoch') AS period
, COUNT(1) AS count
FROM {$this->prefix}entry AS e
{$restrict}
GROUP BY period
ORDER BY period ASC
SQL;

		$stm = $this->bd->prepare($sql);
		$stm->execute();
		$res = $stm->fetchAll(PDO::FETCH_NAMED);

		$repartition = array();
		foreach ($res as $value) {
			$repartition[(int) $value['period']] = (int) $value['count'];
		}

		return $this->convertToSerie($repartition);
	}

}