$start_date = date("Y-m-d H:i:s", strtotime('next Saturday'));
$start_week = date("Y-m-d", strtotime("last week"));
$end_week = date("Y-m-d", strtotime("this week"));
$sat = strtotime('saturday');
$start_date = date("Y-m-d H:i:s", strtotime('Saturday'));
$start = strtotime('2 weeks ago');
格式化日期 2011-01-07T12:22:11 各种用法常见于Java提供的接口
echo date("Y-m-d\TH:i:s", strtotime("2011-01-07 12:22:11"));
$source = '2012-07-31';
$date = new DateTime($source);
echo $date->format('d.m.Y'); // 31.07.2012
echo $date->format('d-m-Y'); // 31-07-2012