下面是一些常用的表示时间的字符:

d -表示一个月中的第一天(01 ~ 31) m -代表一个月(01 ~ 12) Y -年份(四位数) l(小写“l”)-代表星期几 H -以小时为单位的24小时格式(00至23) H -以前导零表示的12小时格式(01到12) i -前导0的分钟(00到59) s -前导0的秒(00到59) a -小写的子午线前后(am或pm)

例子:

echo "Today " . date("Y/m/d") ;
echo "time " . date("h:i:sa");

非常简单 echo $date = date('Y-m-d H:i:s');

// Simply:
$date = date('Y-m-d H:i:s');

// Or:
$date = date('Y/m/d H:i:s');

// This would return the date in the following formats respectively:
$date = '2012-03-06 17:33:07';
// Or
$date = '2012/03/06 17:33:07';

/** 
 * This time is based on the default server time zone.
 * If you want the date in a different time zone,
 * say if you come from Nairobi, Kenya like I do, you can set
 * the time zone to Nairobi as shown below.
 */

date_default_timezone_set('Africa/Nairobi');

// Then call the date functions
$date = date('Y-m-d H:i:s');
// Or
$date = date('Y/m/d H:i:s');

// date_default_timezone_set() function is however
// supported by PHP version 5.1.0 or above.

有关时区参考，请参见支持的时区列表。

我们可以使用date函数设置默认时区:

<?php
    date_default_timezone_set("Asia/Kolkata");
    echo "Today is " . date("Y/m/d") . "<br>";
    echo "Today is " . date("Y.m.d") . "<br>";
    echo "Today is " . date("Y-m-d") . "<br>";
    echo "Today is " . date("l");
    echo "The time is " . date("h:i:sa");
?>

你可以使用下面的代码:

<?php
    $currentDateTime = date('Y-m-d H:i:s');
    echo $currentDateTime;
?>

 $date = new DateTime('now', new DateTimeZone('Asia/Kolkata'));
 echo $date->format('d-m-Y H:i:s');

更新

 //Also get am/pm in datetime:
 echo $date->format('d-m-Y H:i:s a'); // output 30-12-2013 10:16:15 am

对于日期格式，PHP date() Function很有用。