MySQL date_add

By  on  

Here's a quick MySQL tip I wanted to throw your way. I created an event system a while back and one of the requirements of the system was to show events that happened yesterday forward, meaning events older than 2 days were to be hidden. MySQL's date_add will allow you to do just that:

The MySQL Example

SELECT title, venue, url, city, state, DATE_FORMAT(date_starts,\'%b %e\') as formatted_date
FROM events
WHERE date_starts >= DATE_ADD(NOW(), INTERVAL -1 DAY) // yesterday!
ORDER BY date_starts ASC

Note that I'm using a negative date value. You can use a positive date value to get tomorrow, next week, next month, etc..

I like the idea of showing events the from past few days -- they show that there's been action recently. Click here for more about MySQL date_add.

Recent Features

  • By
    39 Shirts – Leaving Mozilla

    In 2001 I had just graduated from a small town high school and headed off to a small town college. I found myself in the quaint computer lab where the substandard computers featured two browsers: Internet Explorer and Mozilla. It was this lab where I fell...

  • By
    CSS Filters

    CSS filter support recently landed within WebKit nightlies. CSS filters provide a method for modifying the rendering of a basic DOM element, image, or video. CSS filters allow for blurring, warping, and modifying the color intensity of elements. Let's have...

Incredible Demos

  • By
    HTML5 Placeholder Styling with CSS

    Last week I showed you how you could style selected text with CSS. I've searched for more interesting CSS style properties and found another: INPUT placeholder styling. Let me show you how to style placeholder text within INPUTelements with some unique CSS code. The CSS Firefox...

  • By
    HTML5 Input Types Alternative

    As you may know, HTML5 has introduced several new input types: number, date, color, range, etc. The question is: should you start using these controls or not? As much as I want to say "Yes", I think they are not yet ready for any real life...

Discussion

  1. Or you can do it like this: date_starts >= NOW() – INTERVAL 1 DAY
    Easier to read in my opinion :) Good tip! I do it like this quite often

  2. macol

    I prefer using php function strtotime() because queries using MySQL functions like NOW() can’t be cached

  3. @macol: Ohhhh, good tip!

  4. Hmm good tip indeed, but… The queries still cannot be cached if you use something as dynamic as strtotime(‘now’), isn’t that right?

    So using strtotime() does not enable the query to be cached? Or am I wrong?
    strtotime() would only give you an advantage if the same query is run during the same second?

  5. If you want caching to work, you can truncate the time part like this:

    $yesterday = strtotime('-1 day');
    $yesterday_str = date('Y-m-d 00:00:00', $yesterday);
    

    Then it’ll be good for the whole day. This has the added benefit of matching the logical meaning of “yesterday” rather than being precicely 24 hours ago.

  6. @Jeremy Parrish: Why didnt I think of this? :) Thanks!

  7. This query will not be used index.

  8. Metric Stormtrooper

    @Niklas Berglund: your query must be deterministic – query might provide same result no matter how many times it is run, if data remains the same. So if your query uses non-deterministic functions such as NOW(), UUID(), RAND(), CONNECTION_ID() etc it will not be cached.
    However, if you pass in a fixed value from PHP as in

    SELECT * FROM logs WHERE logstamp = ”

    it will be cached.

    (the php function today() is just a one-liner that returns the current day in mysql format)

  9. Metric Stormtrooper

    @Metric Stormtrooper: SELECT * FROM logs WHERE logstamp = ‘::php today() ::’

    hm, cant post php syntax here, but you get the idea

  10. Or you can use this: DATE_SUB(NOW(), INTERVAL 1 DAY)

Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!