What is now function in php?

Short answer

$now = date_create()->format('Y-m-d H:i:s');

Read below for the long answer.

The mimicry of the MySQL NOW() function in PHP

Here is a list of ways in PHP that mimic the MySQL NOW() function.

// relative date
$now = date_create('now')->format('Y-m-d H:i:s'); // works in php 5.2 and higher  
$now = date_create()->format('Y-m-d H:i:s'); // also works in php 5.2
$now = new DateTime('now')->format('Y-m-d H:i:s'); // syntax error!!!
$now = (new DateTime('now'))->format('Y-m-d H:i:s'); // works in php 5.4 and higher   
$now = date('Y-m-d H:i:s'); // Slightly higher performance, but less usable for date/time manipulations

// From Unix timestamp
// Using date_create() with a Unix timestamp will give you a FALSE,  
// and if you try to invoke format() on a FALSE then you'll get a: 
//     Fatal error: Call to a member function format() on boolean 
// So if you work with Unix timestamps then you could use: date_create_from_format().
$unixTimeStamp = 1420070400; // 01/01/2015 00:00:00
$y2015 = date_create_from_format('U', $unixTimeStamp, timezone_open('Europe/Amsterdam'))->format('Y-m-d H:i:s');
$y2015 = date('Y-m-d H:i:s', $unixTimeStamp);

I think that date_create()->format('Y-m-d H:i:s') is the best way because this approach allows you to handle time/time-zone manipulations easier than date('Y-m-d H:i:s') and it works since php 5.2.

MySQL NOW() function

The MySQL function NOW() gives the dateTime value in this format: 'YYYY-MM-DD HH:MM:SS'. See here: https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_now.

An interesting fact is that it's possible to get the datetime format by running this query: SHOW VARIABLES LIKE 'd%e_format', the result could be something like this:

Variable_name     Value     
date_format       %Y-%m-%d
datetime_format   %Y-%m-%d %H:%i:%s

The variables up here are read-only variables. So you can't change it.

I guess the MySQL NOW() function gets it's format from the datetime_format variable.

Advantages of using date_create()->format() instead date() summary

The favorable facts of date_create('now')->format('Y-m-d H:i:s') over date('Y-m-d H:i:s') are:

• O.O.P.
• easier to handle time manipulations
• easier to handle timezones

Disadvanteages of using date_create()->format() instead date() summary

• date() performs slightly better

Advantages of using date_create()->format() instead date() detailed

Read on for the detailed explanation.

O.O.P.

The function date_create() is a constructor function for the DateTime object. The documentation of that Object gives the programmer a quick view that describes the possibilities. Documentation: https://www.php.net/manual/en/class.datetime.php

The function date() just gives you a string.

My taste for usability lies in O.O.P.

easier to handle time manipulations

date_create() accepts a relative date/time format (like now, yesterday or +1 day) see this link, example:

$tomorrow = date_create('+1 day')->format('Y-m-d H:i:s'); 

date() accepts a relative date/time format as well, like this:

$tomorrow = date('Y-m-d H:i:s', strtotime('+1 day'));
$tomorrow = date('Y-m-d H:i:s', (time() + 86400)); // 86400 seconds = 1 day

easier to handle timezones

When timezones matter then the usage of date_create()->format() makes a lot more sense then date() because date() uses the default time zone which is configured in php.ini at the date.timezone directive. Link: http://php.net/manual/en/datetime.configuration.php#ini.date.timezone .

It is possible to change the timezone during run-time. Example:

date_default_timezone_set('Asia/Tokyo');.

The downside of that is that it will affect all date/time functions. This problem doesn't exists if you are using date_create()->format() in combination with timezone_open().

PHP supports major timezones. The funny thing is that it even supports the Arctic circle, and Antarctica. Have you ever heard about Longyearbyen? If not, then don't worry, neither did I until I read the official PHP documentation. Does it matter? Well... yes if you run an international e-commerce platform and do something bound to local time, for example: calculate delivery date-time.

$nowLongyearbyen = date_create('now', timezone_open('Arctic/Longyearbyen'))->format('Y-m-d H:i:s');

See a list of all supported timezones: http://php.net/manual/en/timezones.php.

date_create() VS new DateTime()

The favorable facts of date_create() over new DateTime() are:

• Namespaces

Namespaces

If you work in a namespace and want to initialise a DateTime object with the new keyword, then you have to do it like this:

namespace my_namespace;

// The backslash must be used if you are in a namespace.
// Forgetting about the backslash results in a fatal error.
$dt = new \DateTime();

There is nothing wrong with this, but the downside of the above is that people forget sporadically about the backslash. By using the date_create() constructor function you don't have to worry about namespaces.

$dt = date_create(); // in or not in a namespace it works in both situations

Disadvantages of using date_create()->format() instead date()

The function date() has a slightly better performance than date_create()->format(). However, it's only visible if you would instantiate DateTime millions of times. Which might never happen in a real-life situation. However, here is the benchmark test:

$start = time();
for ($i = 0; $i <= 5000000; $i++) {
    $a = date_create('now')->format('Y-m-d H:i:s');
}
$end = time();                  
$elapsedTimeA = $end - $start;
 
echo 'Case date_create(), elapsed time in seconds: ' . $elapsedTimeA;
echo '<br>';
 
$start = time();
for ($i = 0; $i <= 5000000; $i++) {
    $b = date('Y-m-d H:i:s');
}
$end = time();                   
$elapsedTimeB = $end - $start;
 
echo 'Case date(), elapsed time in seconds: ' . $elapsedTimeB;
echo '<br>';
// OUTPUT
Case date_create(), elapsed time in seconds: 31
Case date(), elapsed time in seconds: 14

Examples of date_create()->format()

I use this approach for my projects if I have to fill an array. Like this:

$array = array(
    'name' => 'John',
    'date_time' => date_create('now')->format('Y-m-d H:i:s'), // uses the default timezone
    'date_time_japan' => date_create('now', timezone_open('Asia/Tokyo'))->format('Y-m-d H:i:s'),
);

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