How Can I Determine and Manage MySQL Server's Time Zone Settings?

Obtaining MySQL Server's Current Time Zone

In MySQL, there is a function that helps you retrieve the current time zone settings for both global and client-specific configurations. Here's how you can utilize it:

mysql> SELECT @@global.time_zone, @@session.time_zone;

However, using this method may result in obtaining "SYSTEM" as the returned value, which indicates that MySQL is configured to align with the system's time zone.

Retrieving Time Zone Using PHP

If the "SYSTEM" placeholder is returned, you can leverage PHP to obtain the time zone used by the server's system through the date_default_timezone_get function.

<?php
// Get the system's time zone
$timeZone = date_default_timezone_get();
echo "System time zone: $timeZone";
?>

Considerations for Database Data Time Zone

It's crucial to note that MySQL stores date and time values without including time zone information. This implies that:

mysql> CREATE TABLE foo (timestamp DATETIME) ENGINE=MyISAM;
mysql> INSERT INTO foo (timestamp) VALUES (NOW());
mysql> SET time_zone = '+01:00';
mysql> SELECT timestamp FROM foo;
| timestamp              |
| ---------------------- |
| 2010-05-29 08:31:59     |

mysql> SET time_zone = '+02:00';
mysql> SELECT timestamp FROM foo;
| timestamp              |
| ---------------------- |
| 2010-05-29 08:31:59     |      <== No change

Even though the server's time zone was changed, the stored timestamp remains the same. This is because timestamps in MySQL are not natively time zone aware.

Best Practices for Time Zone Management

To maintain data integrity, it's essential to adhere to the following recommendations:

• Set the time zone appropriately for the server using SET time_zone = ' 00:00'.
• Ensure that any functions that require a time zone, such as now() and unix_timestamp(), are used with the correct time zone.
• Store dates and times in GMT (which does not observe Daylight Savings Time) and convert them to the desired time zone when needed. This ensures consistency and eliminates ambiguity.

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