I have a timestamp column in a db table. Saving values with:
UPDATE `table` SET `activated_at` = CURRENT_TIMESTAMP WHERE `id` = 123;
works fine.
But when I use the php function time() to get the timestamp, it doesn't work. It only works using date('Y-m-d H:i:s') for the column value. Question is why?
the column definition is:
`activated_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00'
I'm using the php mysql extension (and yes, I know it's deprecated, but I have to maintain some legacy code)
Since time() in php return a unix timestamp and timestamp is a datetime type and it requeires a valid datetime value.If you didnt give a valid datetime value it will be storing like 0000-00-00 00:00:00. If you want to keep your field as datetime type then you must give date('Y-m-d H:i:s') in php
Also check the documention of various date time types in mysql
time() returns a unix timestamp, but the MySQL timestamp column supports specific formats such as YYYY-MM-DD HH:II:SS. You can easily do the conversion using date for PHP or FROM_UNIXTIME in mysql.
Look here
The TIMESTAMP data type is used for values that contain both date and time parts. TIMESTAMP has a range of '1970-01-01 00:00:01' UTC to '2038-01-19 03:14:07' UTC.
MySQL converts TIMESTAMP values from the current time zone to UTC for storage, and back from UTC to the current time zone for retrieval. (This does not occur for other types such as DATETIME.) By default, the current time zone for each connection is the server's time. The time zone can be set on a per-connection basis. As long as the time zone setting remains constant, you get back the same value you store. If you store a TIMESTAMP value, and then change the time zone and retrieve the value, the retrieved value is different from the value you stored. This occurs because the same time zone was not used for conversion in both directions. The current time zone is available as the value of the time_zone system variable. For more information, see Section 10.6, “MySQL Server Time Zone Support”
*nix timestamp and MySQL TIMESTAMP is not the same... that's why you need convert from *nix timestamp to MySQL timestamp over date('Y-m-d H:i:s', $unix_timestamp)
if you want to use time() change the column type to varchar(15)
Related
I'm working on something where the user can select their own timezone and the software will be able to be used by others on their sites as well but I want to make sure that the timezone within the database is always set to UTC.
Now I know how you set the default timezone for PHP, such as:
date_default_timezone_set('Australia/Sydney');
...but I'm not sure how to make sure MySQL is using UTC? ...and even once you have made sure it is using UTC I guess you would have to convert your PHP dates/times into UTC before passing it to the database?
I guess I am wondering about many different date formats such as TIMESTAMP, DATETIME & even UNIX EPOCH integer timestamps which would simply be stored as a int datatype for example.
Then there is the whole retrieving dates/times from the DB and converting it to the respective timezone and lastly how does DST come into all of this?
I know there is a lot of similar questions out there, but I guess none really answered all my questions.
MySQL's data type timestamp stores the dates in UTC. For this to work properly, MySQL uses server's time zone and does the date conversion. It converts the date from servers's current time zone to UTC for storage. This implies that the database server should never change its time zone for this feature to work properly.
When you send the data to such a database, you send the UTC time as well. The easiest way to do this is to format a result of time() according to what MySQL wants (m-d-Y H:i:s).
In PHP, when you format the date for insertion to MySQL, it's the best to use DateTime class. It lets you offset the date with the time zone information, meaning that you don't have to use date_default_timezone_set function - that can lead to mistakes.
An example of DateTime in action:
$date = '1.12.2015 13:37:37'; // Format is day.month.year hour:minute:second
// We create DateTime from custom date format, for the person who resides in Australia/Sydney time zone
$dt = DateTime::createFromFormat('d.m.Y H:i:s', $date, new DateTimeZone('Australia/Sydney');
// Now we change the date's time zone into UTC, and we can insert it into MySQL
$dt->setTimeZone(new DateTimeZone('UTC'));
// This is the formatted date-string that can be safely inserted into MySQL
$date_string_for_mysql = $dt->format('m-d-Y H:i:s');
Alternatively, you can use int type in MySQL for timestamp storage and insert result of time() but this has a huge disadvantage of not being able to use date-related functions.
for current session of mysql you can try something like
SET time_zone = timezonename;
for more details you can also look into this answer https://dba.stackexchange.com/questions/20217/mysql-set-utc-time-as-default-timestamp
I have a PHP MySQL query that inserts some data into a MySQL database and it includes a timestamp.
Currently the INSERT query uses NOW() for the the timestamp column and it is saved in the database in the following format: 2012-07-24 13:13:02
Unfortunately for me the Server is not in my time zone and it is listed as America/Los_Angeles as shown print date_default_timezone_get();
I was hoping to do the following:
date_default_timezone_set('Europe/London');
$timefordbLondonEU = date('Y-m-d H:i:s', time());
and simply save into the database the $timefordbLondonEU in place of the NOW();
Is this a good way to save such data ?
Many Thanks,
Richard
[ADDED TEXT]
I changed the Type in the MySQL db to DateTime and did the following:
date_default_timezone_set('Europe/London');
$timefordbLondonEU = date('Y-m-d H:i:s', time());
It is working but Im still not getting the overall concept yet.
Assumptions based on your comments:
MySQL = Does not have a datatype UTC you simply use type INT.
Unix_TimeStamp() will save the current time or count? in UTC format such as 1343247227.
As UTC is a count from a common 0 point you can get any timezone from it. Assuming that you don't want a date before the reference 0 point in 1970.
My guess and lead on from what you have said is the best way to do it is save the time as UTC in an INT (1343247227) and then generate any time zones you want from there. Again assuming you don't need to store dates before the reference 0 point in 1970.
Equally why not store as datetime YYYY-MM-DD HH:MM:SS at a known timezone and then convert to UTC or other timezones. It all seems pretty messy =(
As #Petah said in the comments, store your times in UTC and covert them in the application as needed.
Unix timestamps are in UTC so I usually store my times in the database as timestamps. This saves the headache and confusion of first converting to UTC to insert, and then from UTC when selecting.
That is, make your time field an INT type, and use the function UNIX_TIMESTAMP() in MySQL when you insert, or get the timestamp from PHP using the time() function.
When you fetch the timestamp from the DB it will be in UTC, but when you display it in your PHP application using date(), it will display in the server timezone, or whatever you set with date_default_timezone_set.
Therefore the following two queries will work:
INSERT INTO `table` (id, time) VALUES(NULL, UNIX_TIMESTAMP());
// or
$time = time();
$query = "INSERT INTO `table` (id, time) VALUES(NULL, $time);
If you want to select it from the DB as a DATETIME, you can do this:
SELECT *, FROM_UNIXTIME(time) as dt FROM `table` WHERE 1
The resulting dt column will be in the format yyyy-MM-dd hh:mm:ss.
You can format the numeric timestamp in PHP using date()
If the PHP version you have is 64-bit, you aren't limited to the 1970 - 2036 range, PHP will support 64-bit timestamps, just make sure to use a BIGINT column in MySQL in that case.
Hope that helps.
I have the following date in mysql stored in DATETIME field:
2012-04-16 16:21:54
Than I select it like this:
SELECT UNIX_TIMESTAMP(date) ....
but if I print the hour using php date function I get one hour difference:
echo date("H:i:s", $row->date)
would print:
17:21:54
Without the second parameter, the date function returns correct value. Any ideas?
According to mysql manual -
UNIX_TIMESTAMP(), UNIX_TIMESTAMP(date)
If called with no argument, returns a Unix timestamp (seconds since '1970-01-01 00:00:00' UTC) as an unsigned integer. If UNIX_TIMESTAMP() is called with a date argument, it returns the value of the argument as seconds since '1970-01-01 00:00:00' UTC. date may be a DATE string, a DATETIME string, a TIMESTAMP, or a number in the format YYMMDD or YYYYMMDD. The server interprets date as a value in the current time zone and converts it to an internal value in UTC. Clients can set their time zone as described in Section 10.6, “MySQL Server Time Zone Support”.
with adding 'e' you can get the timezone for that timestamp.
It has probably something to do with different timezones. Try using http://www.php.net/manual/en/function.date-timezone-set.php.
If that won't work, explore the rest of the date function:
http://php.net/manual/en/book.datetime.php
These both correctly return the current UNIX timestamp:
SELECT UNIX_TIMESTAMP(LOCALTIMESTAMP()); #MySql
echo time(); //PHP
But I'm storing UTC_TIMESTAMPs in my database (not LOCALTIMESTAMPs).
How can I convert a UTC datetime to a UNIX timestamp using MySQL?
Note that LOCALTIMESTAMP() is a synonym for NOW(). So what you're really asking is how to get the current time and convert it to GMT and then convert to a unix timestamp to store in the db. So this will work:
SELECT UNIX_TIMESTAMP(CONVERT_TZ(NOW(), ##global.time_zone, 'GMT'));
As an aside, it's always much better to use the time and date columns of a database rather than unix timestamps. It makes querying and displaying results much easier.
Update: Are you sure you are getting what you think you are? UNIX_TIMESTAMP returns a UTC based seconds since the UNIX epoch. It does not return a MySQL DateTime type. If you have an actual UTC DateTime instance, then you can put that directly into your DateTime column of your database and don't have to use UNIX_TIMESTAMP as an intermediary. What type do you actually have that's in local time?
I'm using PHP/MySQL and I've always used DATETIME to store created and updated values, but I'm thinking there may be a better way.
Should I be using TIMESTAMP instead, and if so, why?
The documentation states:
TIMESTAMP values are converted from the current time zone to UTC for storage, and converted back from UTC to the current time zone for retrieval. (This occurs only for the TIMESTAMP data type, not for other types such as DATETIME.) By default, the current time zone for each connection is the server's time. The time zone can be set on a per-connection basis, as described in Section 9.6, “MySQL Server Time Zone Support”. As long as the time zone setting remains constant, you get back the same value you store. If you store a TIMESTAMP value, and then change the time zone and retrieve the value, the retrieved value is different from the value you stored. This occurs because the same time zone was not used for conversion in both directions. The current time zone is available as the value of the time_zone system variable.
So you may want to use TIMESTAMP if you want your date/time stored in UTC instead of in the current time zone.
Timestamps are stored in UTC time in the database. Then, depending on your timezone setting, any time you fetch it it will automatically adjust the offset appropriately. If you are concerned with setting timezones for your application then definitely go with Timestamps.