Mats Lindh

From time to time you’re going to need to move some data from one table into another, in particular to generalize or specialize code. I’ve seen amazingly large code blocks written to handle simple cases as this, and here’s a simple trick you’re going to need some day:

INSERT INTO 
    
    (field_1, field_2) 
SELECT
    some_field, some_other_field 
FROM 
    

You can also add conditionals, i.e. to retrieve rows that might have been inserted yesterday, etc:
INSERT INTO 
    
    (field_1, field_2) 
SELECT
    some_field, some_other_field 
FROM 
    
WHERE
    condition = 1

The good thing about this is that all data movement is kept within the database server, so that the data doesn’t have to travel from the server, to the client and then back from the client to the server again. It’s blazingly fast compared to other methods. You can also do transformations with regular SQL functions in your SELECT statement, which should help you do very simple operations at the speed of light.
	

	
	




	
	

		
A Plugin for Paginating in Smarty
	


	

		
First I’d like to apologize for the lack of updates here in the last weeks, but the days have been very busy. I’ve bought a new car (more details about that as soon as the snow disappears), written a complete publishing platform from scratch in a weekend to help out when Gamer.no got in trouble and in general done a load of stuff. Anyways, this post isn’t about all that, but rather something else I wrote some time ago.
A use case you’ll encounter very often is the act of paginating items, i.e. including a simple “jump to page x, jump to the next page, jump to the previous page” footer. If you’ve ever tried to implement the logic around this in your view, you know that it can get quite extensive. You have several other solutions, such as the PEAR_Pager, which actually looks like a good solution now (with 2.x). Anyways, this is a plugin for Smarty to make generating pagination links easier.

Download
Source

Download the plugin, drop it into your plugins/ folder in your Smarty library directory, and voilá, you have access to the new {paginator} element.
The module is quite configurable, but as I’ve only extended the parts I’ve had use for it our projects, it may still lack a few simple keys.
{paginator hits=$hits offset=$offset total_hits=$articlesFound class_inactive=paginatorInactive class_active=paginatorActive}

The template variables used here are hits, the number of hits shown on this page, offset, the offset from 0 and total_hits, the total number of available hits in the current list. By default the plugin appends ?hits=<hits>&offset=<offset>+<hits> to the current URL, you can give another URL through the url attribute. The class_ attributes provide the CSS classes to use for the elements that enclose the page numbers or links. See the source code (!) for more information about attributes which work.
As I mentioned previously, the plugin is written for my own personal use, so it’s not as streamlined as it could be. Feel free to update it, dissect it, break it, claim it’s yours .. or anything. I’d be happy if you submit any patches to me so I can update the link here, or simply leave a comment.

Download
Source

Hack aways! You can see the plugin in action at the bottom of lovethatfun.com.
	


	
	




	
	

		
Undefined symbol: php_pdo_declare_long_constant
	


	

		
After installing a new PDO module (PDO_PgSQL) into our compiled-from-the-ground-up version of PHP 5.2.8 (.. since RHEL4 doesn’t really stay updated, but we do), i ran head first into the following issue:


/usr/sbin/httpd: symbol lookup error: /usr/local/lib/php/extensions/no-debug-non-zts-20060613/pdo_pgsql.so: undefined symbol: php_pdo_declare_long_constant


Panic. Then tried updating pdo_mysql which actually still worked, which just led it to have the exact same problem. Luckily a bit of searching at Google pointed me to PDO_MYSQL causing Apache segfault over at the PECL bug tracker. The last comment provided the solution to the problem: a quick rebuild of PHP with –disable-pdo and then enabling pdo from PECL instead (so that PDO and the PDO plugins API actually match, instead of trying to load the wrong version into the process) solved the issue.
Be sure to build PDO from the SAME VERSION as your client libraries. Disable it in the PHP build itself if you need to build it from PECL.
	


	
	




	
	

		
Removing (dropping) a Foreign Key Constraint in PostgreSQL
	


	

		
Had a need to drop a Foreign Key Constraint in PostgreSQL 8.x today, and this is how you do it:



database=> \d table_name;

     Table "public.table_name"

      Column      |          Type          | Modifiers

------------------+------------------------+-----------

 id           | integer                |

 field        | character varying(20)  |

 field_description | character varying(150) |

Indexes:

    [..]

Foreign-key constraints:

    "table_name_id_fkey" FOREIGN KEY (id) REFERENCES other_table(id) ON DELETE CASCADE

database=> ALTER TABLE table_name DROP CONSTRAINT "table_name_id_fkey";

ALTER TABLE

database=>


As simple as that. The name of the constraint is shown when describing the table with \d under “Foreign-key constraints”, and you simply do an ALTER statement to drop the constraint.
	


	
	




	
	

		
The Power of Creative Commons
	


	

		
Creative Commons provides a set of tools that allow author, publishers, etc. to explicitly license their content for a broader set of fair use than regular Copyright law allows. This increases the usefulnes of the creation and allows other to build further on your own creation. Sounds scary for some people, sounds like a dream for other. 
Ever since I started uploading my photos to flickr (I’m doing quite a bit of photography in my spare time), I’ve tried to make most of them available under the most free Creative Commons license. The few exceptions are photos featuring people, where I usually don’t have explicit permission from the persons to license the photo freely. I’ve also made the same exception for cars with visible license plates, as that will identify the person owning the car. Otherwise, I’ve tried to publish my photos under a Creative Commons Attribution Only license.
 While I probably had the same reservations as most people had when I first looked into relicensing my photos, my experiences so far has only been positive. I’m still amazed to find new ways people are using my images every now and then, and possibly the most surprising usage of any of my images were found today:
In the norwegian local historic wiki, one of my images of two goats at Nordens Ark in Sweden is used as an example of how a Geitbåt (A goat boat) resembles the stretched neck of a goat. Amazing. If you ever go to read about the danish city of Elsinore (Helsingør) on Wikipedia (or Kronborg Castle), the image of the main land mark of the city was taken by yours truly. My images has been on cnbc.com, featured in online travel guides, in articles about how to save money on used games, in self improvement guides, in a farmer’s guide in connecticut about cows, in an english textbook and surely loads of other places. The alternative would have been that all the photos had been sitting on flickr, alone by themselves and possibly seen by .. 2 people. If that many. And one of them would have been me.
My tip: License all your stuff as freely as possible and watch the world use it in ways you never had imagined. 
I like this world. And I’ll try to license my photos under the newest CC license as long as I’m finding the fun in taking pictures. Awesome. 
Update: A friend of mine, Vegard, discovered that his photo of one of NSB’s BM93s is featured on the front page of Wikipedia today (21st of January, 2009). Wonder how many people have seen that image now…
	


	
	




	
	

		
Redesigning the “Sign Up Team” Form at pwned.no
	


	

		
I’ve spent a couple of days on and off redesigning the “sign up a team” at my tournament site, pwned.no. The currently live form is divided into two sections, depending on wether you want to sign up one of your existing teams or want to just sign up a temporarily created team — or one you haven’t created a proper team for yet:

I’m not happy about the fact that the form is actually divided into two parts, meaning that you have to read two sections to actually understand that you can sign up with an existing team – or write the name of one right there. The forms also have information that are common for both forms, so we’re duplicating a few user interface elements.
The new form still lack a bit of functionality to dynamically enable and disable the submit button based on the selection in the form, but since disabling the form made it look uglier than ugly, I haven’t added that bit yet. The screenshots also differs a bit since Opera and Firefox doesn’t quite agree on the double border CSS.
The new, complete version:

And if you don’t have any existing teams (clans) available, the form now includes a link to the page where you can create one – and try to explains why you should do that.

Also, if you’re not logged in, you’re just presented with the simple form. I think I’m going to add a notice about signing in with a bit of text in the same gist as the create clan bit.

Hopefully this will help reduce any confusion, but luckily the form is quite small anyways. I’ve also added more proper error hilighting, both before signing up and after failing to do so for any reason. Small fixes, but they should increase usability.
Any suggestions of potential ways to enhance this form even more would of course be appreciated!
	


	
	




	
	

		
Pinouts for the Guitar Hero World Tour Wireless Controller
	


	

		
If you’ve ever wondered exactly which buttons correspond to which pins on the internal layout of the Xbox 360 Guitar Hero World Tour Wireless Controller, look no further! If you ever see the insides of such a controller and are wondering exactly which buttons are designated to which pins or wires, this can save you the trouble of opening both the neck and the base:
Green (A): 1 + 8

Red (B): 2 + 7

Yellow (Y): 2 + 6

Blue (X): 2 + 3

Orange (LB): 4 + 5
Attach a multimeter to measure the resistance between the two pins for each button, and you’ll see the value drop towards zero each time you press the corresponding button. This is very useful for debugging an issue where one of the buttons seems broken.
Good luck!
	


	
	




	
	

		
The Side Effect of Using Return Type To Handle Errors
	


	

		
I came across a curious little side effect of the issue I just posted earlier:
public function action()
{
   $id = filter_input(INPUT_POST, 'id', FILTER_SANITIZE_STRING);
	
   if(is_bool($id))
   {
      die('invalid id');
   }

   if(isset($_POST['accept']))
   {
      $this->acceptId($id);
   }
   else if(isset($_POST['reject']))
   {
      $this->rejectId($id);
   }
}

This is obviously going to do something when a POST has occured, but the method was invoked each and every time. The reason why it works? If there is no variable named ‘id’ POSTed, filter_input returns null. And null is not boolean, so the test passes. But as it’s not a POST request, neither of the two other if-tests are true, so the code silently passes through (id can contain characters here, so the filter isn’t used to just get integers).
If you’re not going to throw an error when the parameter is missing, the test is actually completely useless. This bug had hidden itself within the usage of the type to test for fault instead of actually checking the value, and did not creep out before I rewrote the if-test.