Date ranges in PHP

date_range.php

<?php

    private function _getDataRange($range)
    {
        $lowerdate = null;
        $upperdate = null;

        switch ($range) {
            case 'today':
                $lowerdate = date('Y-m-d 00:00:00');
                $upperdate = date('Y-m-d 23:59:59');
                break;

            case 'yesterday':
                $lowerdate = date('Y-m-d 00:00:00', strtotime('-1day'));
                $upperdate = date('Y-m-d 23:59:59', strtotime('-1day'));
                break;

            case 'this_month':
                $lowerdate = date('Y-m-d 00:00:00', strtotime('first day of this month'));
                $upperdate = date('Y-m-d 23:59:59',strtotime('last day of this month'));
                break;

            case 'this_week':
                $lowerdate = date('Y-m-d 00:00:00', strtotime('last monday'));
                $upperdate = date('Y-m-d 23:59:59',strtotime('next sunday'));
                break;

            case 'last_30_days':
                $lowerdate = date('Y-m-d 00:00:00', strtotime('-30days'));
                $upperdate = date('Y-m-d 23:59:59');
                break;

            case 'last_10_minutes':
                $lowerdate = date('Y-m-d H:i:s', strtotime('-10min'));
                $upperdate = date('Y-m-d H:i:s');
                break;

            case 'last_60_minutes':
                $lowerdate = date('Y-m-d H:i:s', strtotime('-60min'));
                $upperdate = date('Y-m-d H:i:s');
                break;

            default:
                break;
        }

        return array($lowerdate, $upperdate);
    }