I am trying to optimise how I use dates across my SQL/PHP site. I'm familiar with date() and strtotime() functions, and have created projects which have stored data on the server side in both unix and datetime. I know that changing date doesn't use massive amounts of resource, but I'm trying to understand how to code in the most efficient way.
What I'm trying to work out now is what the quickest/most efficient practise is for storing dates on a server, i.e: What is the most effective combination of SQL FROM_UNIXTIME, CONVERT, UNIX_TIMESTAMP and PHP strtotime and date functions, for a typical table involving frequent CRUD of the date fields. Take the following example:
I have an SQL table which contains 3 date columns. All 3 of these can be updated quite regularly by multiple users of the site, and entries are also entered in to it as follows:
mysql_query("INSERT INTO `regular` (
`regularid`,
`propertyid`,
`userid`,
`billdate`,
`billfrequency`,
`enddate`,
`amount`,
`description`,
`payee`,
`payer`,
`lastpayment`
)
VALUES (
'', '{$_POST['propertyid']}', '$varuserid', FROM_UNIXTIME($date), '{$_POST['billfrequency']}', 'FROM_UNIXTIME($edate)', '$amount', '{$_POST['description']}', '{$_POST['payee']}', '{$_POST['payer']}', 'FROM_UNIXTIME($ldate)'
)") or die(mysql_error);
Print "A regular payment for £".$_POST['amount']." has been created<br/>\n";
Entering in to the database I parse the date fields from a user entry form to a variable in mm / dd / yyyy format, validate it with the strtotime() or mktime() functions, and then submit it using from_unixtime.
However, then displaying information from the database I use:
date("d-m-Y", strtotime($val['billdate']))
That means I take a dd/mm/yyyy date format from the user and another one from the database. I then convert these to unixtime using strtotime, and then convert it back to British date format using date - This is surely doubling? if not tripling? the server query.
My question is in 2 parts.
Firstly, is it quickest a) storing all date formats in unixtime in sql and converting to date format through the server side query or b) storing all date formats in date format and converting to unixtime only when accessing them
(I thought the latter would be best, but my example above shows that even doing that I seem to be using more server time than I ought to)
Secondly, could you point me in the right direction for how I should carry out my own time benchmarks of scripts - I'm only really beginning to understand testing as I'm still relatively new to Php, but I'm keen to learn.
Thanks so much!
Use MySQL's "unix_timestamp()", it's short and can be converted to readable full date within a second by using php, bash etc.
Related
I've been reading about storing and displaying dates and times in mySQL, but I don't seem to find an answer that suits my needs or I'm incapable of coding my own one. I guess being full of doubts doesn't help at all.
The thing is, I have a mySQL table with a field (text) which I would like to contain certain times and dates. At the moment I'm working with "d/m/Y H:i" format, but I'm pretty sure that's not neat. I'm using that format because it's the format I want it to be displayed on the site.
Could anyone tell me what the correct way of handling this issue would be? Maybe I have to store the date and time in another format and convert it when it's going to be be displayed on the site.
You should store them as TIMESTAMP or DATETIME (check the differences here)
and then convert them when you write or read the values, for example:
INSERT INTO table (date_time) VALUES (CURRENT_TIMESTAMP)
SELECT date_format(date_time, '%b %d %Y %h:%i %p') as date_time FROM table ...
i would say your guess would be the best way to do it. Store it in seconds since EPOCH and then convert using any multitude of ways that php offers:
take a look at this:
epoch time stamp
the epoch time stamp is valid for ANY time zone. Which makes your server location not important. You could show time for any time zone as long as your parse it correctly with php (or you could even do it client-side with JS)
It seems like there are too many complicated ways of doing this, so I'm looking for a clean, succinct answer to this issue.
I write a blog, I click submit, and the title, content, and timestamp INSERTS INTO my blog table. Later, the blog is displayed on the blogindex.php page with the date formatted as MM-DD-YYYY.
So this is my 3 step question:
What is the best column type to insert the date into? (ex: INT, VARCHAR, etc)
What is the best INSERT INTO command to use? (ex: NOW(), CURDATE(), etc)
When I query the table and retrieve this data in an array, what is the best way to echo it?
I'm new at PHP/MySQL, so forgive me if I don't know the lingo and am too frustrated reading 1000 differing opinions of this topic that do not address my issue specifically, or only cover one of the 3 questions...
Here is my opinion on your three questions:
Use the correct data type: Date or DateTime. I would choose for the DateTime type as you store the time as well (might be very handy if you want to have some kind of order, when you added the posts).
It all depends whether you just want the Date (use CURDATE()) or the Date + Time (use NOW()).
You fetch the data and format it how you want it. Don't format it yet in the query, just use the correct PHP functions for it (for example with DateTime). How you fetch the data, doesn't matter too much; you can use PDO or MySQLi or ...
Always store and process dates and times in UTC and perform timezone adjustments in your presentation layer - it considerably simplifies things in the long-term.
MySQL provides a number of different types for working with dates and times, but the only one you need to worry about is DATETIME (the DATE type does not store time information, which messes up time zone conversion as information is lost, and the TIMESTAMP type performs automatic UTC conversion (which can mess up programs if the system time zone information is changed) and has a smaller range (1970-2038).
The CURDATE() function returns only the current date and excludes time information, however this returns information in the local timezone, which can change. Avoid this. The NOW() function is an improvement, but again, returns data in the current time zone.
Because you'll want to keep everything in UTC you'll actually want to use the UTC_TIMESTAMP function.
To return the value you'll need to execute SQL commands in sequence with variables, like so:
SET #now = UTC_TIMESTAMP()
INSERT INTO myTable ( utcDateTimeCreatedOrSomething ) VALUES ( #now )
SELECT #now
Date would probably be the best type, although datetime will work as record more accurate as well.
There isn't a 'best insert into', but what do you really want and how accurate you want the date to be. For a blog, I would say make it datetime and use NOW(). so visitors can see quite accurate of when this post is made.
surely you can easily find huge to run sql and fetch a select query from sql using php by google, so I'll leave this easy work to your self.
For echo the date, you can use the php date format such as:
$today = date("m-d-y"); // 03-10-01
I think Styxxy has it pretty well right, but here is a links for your PHP date formatting part...
How to format datetime most easily in PHP?
(Supporting link: http://php.net/manual/en/datetime.format.php )
Basically it's
echo date("d/m/Y", strtotime('2009-12-09 13:32:15'))
... although, I think the strtotime is unnecessary as it should already have the type of datetime.
In terms of the MySQL, yes, do it as a datetime col, use NOW() as the SQL keyword, and depending on how you want to get it from the database you could...
SELECT CAST(col_name AS DATE) .... or .... SELECT CAST(col_name AS DATETIME) <-- this last one is implied due to the col type.
good luck! :)
I have a DATETIME string and I need only the DATE in my script to perform some searches in my database. Currently, I have two scenarios in my mind, but don't know which of them is faster.
The first scenario:
In my MYSQL database, I have two columns: datetime (which is a DATETIME type) and date (which is a DATE type).
Then, in my PHP script, each time I save a record, I will insert my known string to the datetime field, and then convert it to fit the date field (I was thinking of something like: $date = date("Y-m-d", strtotime($datetime))).
This way, all the necessary pieces are stored in my database and I can retrieve them on the fly (both the datetime and the date fields).
The second scenario:
The MYSQL database should consist only of the datetime column.
My PHP script will insert the known string to the datetime field without any other modifications.
And when I retrieve my data, I would do something like: SELECT datetime, DATE(datetime) FROM ...
Conclusion
Which of these scenarios is faster and therefore should be used? Should date formats be made on save or on retrieve? Is MYSQL faster than PHP on formatting dates? Is it better to store everything in the database and retrieve as it is, or store only the minimum and format on retrieve? Which of these scenarios is the best practice?
Thank you!
It depends of your usecases:
If you are only going to need the date for reading, then go with a single datetime column, conversion from datetime to date is cheap enough.
If you are going to select rows at a given date (like WHERE date = '2011-08-01'), then go for a date column, as this will allow mysql to use the indexes on the date column if you have added one.
If you are going to select rows in a date range, then go for a datetime column. You could do things like WHERE datetime >= '2011-08-01' AND datetime < '2011-08-16'.
The second one is the best and fast as you are getting the value based on the requirement. Rather getting some value and working on it later.
imho
datetime, or even unsigned integer (unix timestamp) is better for range filtering
datetime allow date-time function, it could be useful for aggregate function
avoid formatted data from mysql (that's mean raw)
anything related to presentation is PHP duty
Definitely depends on your situation - if you will be reading (a lot) more than writing, you can store both. But I'd go for storing one field (datetime) and convert that, either in PHP or while retrieving it from MySQL (convert datetime to char in the format you like)
In my php application I have this code:
<?php echo date("d/m/ Y ",strtotime($row["m_date"]));?>
In it, $row["m_date"] is fetching from a database.
The problem is that all the dates are printing perfectly except 27/2/2011. It's printing 1/1/1970 instead.
The date in the database is fine, and prints correctly in a PDF.
I'll assume you're getting the date from the database as the string 27/2/2011 because that's most probably what happens (correct me if I'm wrong).
PHP considers the string 27/2/2011 as being in the m/d/Y format, not d/m/Y and tries to parse under that assumption. Because the date is not valid under that format strtotime returns false. Giving false as the timestamp parameter to date is taken as 0, which is the timestamp for January 1st 1970.
What you need to do is either get your date in another format (or better still, as a timestamp) from the database, or parse it yourself (say using explode).
Good luck,
Alin
The database should be able to return the date to you as a UNIX timestamp. For example, MySQL has the UNIX_TIMESTAMP() function.
SELECT UNIX_TIMESTAMP(date_column) FROM table;
Postgres has date_part
SELECT DATE_PART('epoch', date_column) FROM table;
Most other databases should have similar features. If you can get the date out as a UNIX time stamp you can pass that directly to date() without having to use strtotime() as well.
All of this does of course assume you're using a temporal datatype for the columns in question (timestamp, datetime, timestamp with time zone, etc) and not just storing a string. You are using a temporal type, right? If not, then why not?
if you are storing the date in the database as a timestamp this should work
<?php echo date("d/m/Y",$row["m_date"]);?>
if you are storing the date in the database as a date or datetime this should work
<?php echo date("d/m/Y",strtotime($row["m_date"]));?>
How is the m_date stored in the databases? Is it a datetime object? Or a string.
Problem with strtotime is that it isn't real good at deciphering written dates. So something like 27/2/2011 gives problems while 27/02/2011 gives no problems at all.
So there are 2 solutions:
Make sure all the dates that get entered into the database are of the correct format (dd/mm/yyyy).
Write a regular expression that adds a leading zero to all single characters.
I have found a proper solution to my "problem" but even after reading mysql pages, I don't understand the logic behind it.
I currently store registration information in my system in a "datetime" formatted field in one of my tables (YYYY-MM-DD hh:mm:ss).
When I want to display the data on one of my php pages, simply posting the exact field data shows the format mentioned above.
I would THINK simply using date("Y-m-d",$row["DATE"]) where $row["DATE"] corresponds to the particular row value would return the desired format.
Instead I have to use:date("Y-m-d", strtotime($row["DATE"])).
Why is this? My $row["DATE"] field is not a string in the first place. Should I be able to simple rearrange the data stored in a datetime field? Wasn't that the purpose of rebuilding my entire tableset to accomodate datetime?
MySQL has a built in function called date_format which you can use to display the date how you want to.
SELECT DATE_FORMAT(date_field, '%Y-%m-%d') as date_field FROM table_name
The manual has the list of formats and the variables needed to display it that way. Using this method there will be no need to have PHP convert it etc. Plus it is less code on PHP side for something MySQL can handle easily.
EDIT
Sorry, just read you were looking for an explanation.
PHP's date function takes in a UNIX timestamp, which MySQL is not using. MySQL uses a real date format IE: YYYY-MM-DD HH:MM:SS, as you know, this is to be compliant for years later. The UNIX timestamp has a limited range from something like 1969 to 2037 that it is valid for, which makes it really useful for "timestamping" of items such as a chat box message or items they are not expected to be around post those dates, where as the MySQL DATETIME should not die out until the year changes to 5 digits or the world ends.
Read the WIKI on UNIX timestamp for more information on it.
MySQL does allow you to select dates in unix timestamp format, which allows them to be used more easily in PHP, exactly as you requested.
The previous answer seemed to ignore this point, or downplay it due to the range restriction on the unix timestamp, but if it's what you're looking for...
SELECT UNIX_TIMESTAMP(datefield) as u_datefield FROM table
will give you the date in timestamp format, which you can use as you suggested in PHP:
<?php
$showdate = date("Y-m-d",$row['u_datefield']);
?>
As the previous answer suggests, unix timestamps do have a limited range, so if you need dates prior to 1970 or after 2038 it may not be suitable, but for everyday use today it's great.
The main advantage of using timestamps over date strings is that timestamps can be added and subtracted, which is much harder with a date in string format.