php 获取不同时段时间戳

$week=date('w');
$week==0?$week=7 //如果是周日回返回零，若一周从周日开始则不需要该语句
switch ($this->Arg['time_range']) {
    case '0'://今天时间戳
        $Group = '`Y`,`M`,`D`';
        $start_time = mktime(0, 0, 0, date('m'), date('d'), date('Y'));
        $end_time = mktime(0, 0, 0, date('m'), date('d') + 1, date('Y')) - 1;
        break;
    case '1'://昨天时间戳
        $Group = '`Y`,`M`,`D`';
        $start_time = mktime(0, 0, 0, date('m'), date('d') - 1, date('Y'));
        $end_time = mktime(0, 0, 0, date('m'), date('d'), date('Y')) - 1;
        break;
    case '2'://本周时间戳
        $start_time = mktime(0, 0, 0, date('m'), date('d') - $week + 1 - 0, date('Y'));
        $end_time = mktime(23, 59, 59, date('m'), date('d') - $week + 7 - 0, date('Y'));
        $Group = '`Y`,`M`,`D`';
        break;
    case '3'://上周时间戳
        $start_time = mktime(0, 0, 0, date('m'), date('d') - $week + 1 - 7, date('Y'));
        $end_time = mktime(23, 59, 59, date('m'), date('d') - $week + 7 - 7, date('Y'));
        $Group = '`Y`,`M`,`D`';
        break;
    case '4'://本月时间戳
        $start_time = mktime(0, 0, 0, date('m'), 1, date('Y'));
        $end_time = mktime(23, 59, 59, date('m'), date('t'), date('Y'));
        $Group = '`Y`,`M`,`D`';
        break;
    case '5'://上月时间戳
        $start_time = mktime(0, 0, 0, date('m') - 1, 1, date('Y'));
        $end_time = mktime(23, 59, 59, date('m') - 1, cal_days_in_month(CAL_GREGORIAN, date('m') - 1, date('Y')), date('Y'));
        $Group = '`Y`,`M`,`D`';
        break;
    case '6'://今年
        $start_time = mktime(0, 0, 0, 1, 1, date('Y'));
        $end_time = mktime(23, 59, 59, 12, 31, date('Y'));
        $Group = '`Y`,`M`';
        break;
};