PHP 获取今天，昨天，前天，过去7天，过去30天，本周，上周的开始和结束时间

protected function selectTime($key)
{
        switch ($key) {
            //今天
            case 1:
                $time[0] = mktime(0,0,0,date('m'),date('d'),date('Y'));
                $time[1] = mktime(0,0,0,date('m'),date('d')+1,date('Y'))-1;
                break;
            //昨天
            case 2:
                $time[0] = mktime(0,0,0,date('m'),date('d')-1,date('Y'));
                $time[1] = mktime(0,0,0,date('m'),date('d'),date('Y'))-1;
                break;
            //前天
            case 3:
                $time[0] = mktime(0,0,0,date('m'),date('d')-2,date('Y'));
                $time[1] = mktime(0,0,0,date('m'),date('d')-1,date('Y'))-1;
                break;
            //过去7天
            case 4:
                $time[0] = mktime(0,0,0,date('m'),date('d')-7,date('Y'));
                $time[1] = mktime(0,0,0,date('m'),date('d'),date('Y'))-1;
                break;
            //过去30天
            case 5:
                $time[0] = mktime(0,0,0,date('m'),date('d')-30,date('Y'));
                $time[1] = mktime(0,0,0,date('m'),date('d'),date('Y'))-1;
                break;
            //本周
            case 6:
                $time[0] = mktime(0, 0, 0, date('m'), (date('d') - (date('w')>0 ? date('w') : 7) + 1), date('Y'));
                $time[1] = mktime(0, 0, 0, date('m'), (date('d') - (date('w')>0 ? date('w') : 7) + 7), date('Y'));
                break;
            //上周
            case 7:
                $time[0] = mktime(0,0,0,date('m'),date('d')-date('w')+1-7,date('Y'));
                $time[1] = mktime(23,59,59,date('m'),date('d')-date('w')+7-7,date('Y'));
                break;
            //本月
            case 8:
                $time[0] = mktime(0,0,0,date('m'),1,date('Y'));
                $time[1] = mktime(23,59,59,date('m'),date('t'),date('Y'));
                break;
            //上月
            case 9:
                $time[0] = mktime(0, 0 , 0,date("m")-1,1,date("Y"));
                $time[1] = mktime(23,59,59,date("m") ,0,date("Y"));
                break;
        }
        return $time;
}