How can I synchronize PHP\'s and MySQL\'s timezones within my web application without modifying server configurations?

Synchronizing Timezones in PHP and MySQL

In web applications, accurately handling datetime values across different timezones is crucial. However, the default timezone settings of PHP and MySQL can differ, leading to discrepancies in date calculations. This article explores the challenges in setting timezones in both PHP and MySQL and provides a comprehensive solution without modifying server configurations.

The Dilemma: Different Timezones

When using PHP's date() function, such as date('Y-m-d H:i:s'), the PHP timezone setting is applied. Conversely, MySQL's NOW() function uses the MySQL server's timezone setting. This mismatch can result in incorrect date comparisons and calculations.

Unsuccessful Attempts

The developer has previously attempted various methods to change the timezone, including:

• Using date_default_timezone_set('Europe/Paris') affects only PHP.
• Setting date.timezone via PHP does not impact MySQL.
• Using SELECT CONVERT_TZ(now(), 'GMT', 'MET') returns an empty result.
• Issuing SET time_zone = 'Europe/Paris' in the MySQL console fails.

Solution: Synchronization

To synchronize the PHP and MySQL timezones within the application, the following approach is recommended:

1. PHP Timezone Configuration

<code class="php">define('TIMEZONE', 'Europe/Paris');
date_default_timezone_set(TIMEZONE);</code>

Define a constant TIMEZONE and use it to set the default timezone for PHP.

2. MySQL Timezone Calculation

<code class="php">$now = new DateTime();
$mins = $now->getOffset() / 60;
$sgn = ($mins < 0 ? -1 : 1);
$mins = abs($mins);
$hrs = floor($mins / 60);
$mins -= $hrs * 60;
$offset = sprintf('%+d:%02d', $hrs*$sgn, $mins);

Calculate the offset between the server time and the desired timezone.

3. MySQL Timezone Setting

<code class="php">// Your DB Connection - sample
$db = new PDO('mysql:host=localhost;dbname=test', 'dbuser', 'dbpassword');
$db->exec("SET time_zone='$offset';");</code>

Execute a query to set the MySQL timezone to the calculated offset.

By implementing this solution, the PHP and MySQL timezones within the application will be synchronized, ensuring accurate datetime calculations and comparisons regardless of server configurations.

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