<?php
/**
 * 上XXX时间函数，用于计算上一周，上n周，上个月，上个季度的时间点。
 *
 * @author bourneli(李伯韬)
 * @date 2012-12-18
 */
/**
 * 获取上个季度的开始和结束日期
 * @param int $ts 时间戳
 * @return array 第一个元素为开始日期，第二个元素为结束日期
 */
function lastQuarter($ts) {
    $ts = intval($ts);
    $threeMonthAgo = mktime(0, 0, 0, date('n', $ts) - 3, 1, date('Y', $ts));
    $year = date('Y', $threeMonthAgo);
    $month = date('n', $threeMonthAgo);
    $startMonth = intval(($month - 1)/3)*3 + 1; // 上季度开始月份
    $endMonth = $startMonth + 2; // 上季度结束月份
    return array(
        date('Y-m-1', strtotime($year . "-{$startMonth}-1")),
        date('Y-m-t', strtotime($year . "-{$endMonth}-1"))
    );
}
/**
 * 获取上个月的开始和结束
 * @param int $ts 时间戳
 * @return array 第一个元素为开始日期，第二个元素为结束日期
 */
function lastMonth($ts) {
    $ts = intval($ts);
    $oneMonthAgo = mktime(0, 0, 0, date('n', $ts) - 1, 1, date('Y', $ts));
    $year = date('Y', $oneMonthAgo);
    $month = date('n', $oneMonthAgo);
    return array(
        date('Y-m-1', strtotime($year . "-{$month}-1")),
        date('Y-m-t', strtotime($year . "-{$month}-1"))
    );
}
/**
 * 获取上n周的开始和结束，每周从周一开始，周日结束日期
 * @param int $ts 时间戳
 * @param int $n 你懂的(前多少周)
 * @param string $format 默认为'%Y-%m-%d',比如"2012-12-18"
 * @return array 第一个元素为开始日期，第二个元素为结束日期
 */
function lastNWeek($ts, $n, $format = '%Y-%m-%d') {
    $ts = intval($ts);
    $n  = abs(intval($n));
    // 周一到周日分别为1-7
    $dayOfWeek = date('w', $ts);
    if (0 == $dayOfWeek)
    {
        $dayOfWeek = 7;
    }
    $lastNMonday = 7 * $n + $dayOfWeek - 1;
    $lastNSunday = 7 * ($n - 1) + $dayOfWeek;
    return array(
        strftime($format, strtotime("-{$lastNMonday} day", $ts)),
        strftime($format, strtotime("-{$lastNSunday} day", $ts))
    );
}
//---------------------demo---------------------
$now = strftime('%Y-%m-%d', time());
echo "Today: {$now}n";
list($start, $end) = lastNWeek(time(), 1);
echo "Last 1 week:  {$start} ~ {$end}n";
list($start, $end) = lastNWeek(time(), 2);
echo "Last 2 week:  {$start} ~ {$end}n";
list($start, $end) = lastNWeek(time(), 3);
echo "Last 3 week:  {$start} ~ {$end}n";
list($start, $end) = lastMonth(time());
echo "Last month:   {$start} ~ {$end}n";
list($start, $end) = lastQuarter(time());
echo "Last quarter: {$start} ~ {$end}n";
?>执行结果如下：

201212181818413855