How to generate date in php

I have this urgent question about date in php. I want to query the database for certain records before a certain date, say I want records within 30 days, so first thing is I get current date, and I want to calculate the o开发者_StackOverflow中文版ther end of the date range, how can I do that? Do I need to do this in mysql query or in php? Much appreciated!

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You can easily do that in mysql.

eg.

SELECT * from myTable where date_column > date_sub(now(), interval 30 day);

now() or CURRENT_TIMESTAMP -> will give you a value of current date. date_sub, and date_add are functions used to add or subtract interval from given date.

Documentation here : http://dev.mysql.com/doc/refman/5.5/en/date-and-time-functions.html#function_date-add

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You can Generate the Current Date in PHP like this:

$current_date = date("Y-m-d"); // the output will be in the format YYYY-MM-DD
echo $current_date;

You can learn more about PHP dates and Date formats here: http://php.net/manual/en/function.date.php

You can also select certain rows from a DB Table using WEEK() and MONTH() . I asked a question related to it yesterday : MySQL: Select data from a table where the date falls in the current Week and current Month

Hope it solves your problem.

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It's generally considered better practice to construct the intervals in php than use MySQL's built-in functions (such as NOW()). There's a very good reason for that.

Suppose you use a query using NOW() (SELECT t.foo, t.bar FROM table t WHERE created_at > DATE_SUB(NOW(), interval 30 day);). The function returns a date with an accuracy down to the last second (e.g '2006-04-12 13:47:36'). Caching this query is quite useless as it is worthwhile for only this 1-second period.

Most applications hardly require this level of accuracy and generally an accuracy of 1 day is good enough. You can already see that constructing a query with less accuracy is a lot more beneficial as the result is cached the first time and any subsequent queries will hit the cache for a whole day.

Here is an example in PHP

$pdo = new \PDO($dsn, $db_user, $db_pass);

$sql = 'SELECT t.foo, t.bar FROM table t WHERE t.created_at >= ?';
$stmt = $pdo->prepare($sql);
$stmt->bindValue(1, date('Y-m-d', strtotime('-30 days')));
$stmt->execute();

For more information about PDO, take a look at the documentation