Gordon P. Hemsley

Linguist by day. Web developer by night.

Posts Tagged ‘humph’

PHP, MySQL, and the BIT field type

Posted by Gordon P. Hemsley on February 8, 2010

As Dave Humphrey once taught me:

When you do a search, and it comes back with no results, it’s a sign that you need to write something.

This is an issue that I came across while testing SASHA (which is available for you to try out, by the way), and I didn’t know if it was a bug or a feature. I could find no mention of it anywhere, and the people in the #mysql IRC channel on FreeNode weren’t especially helpful in helping me get to the bottom of it.

What is the issue, you ask? Well, even that in and of itself is a question, because I don’t know whether it’s a bug (or feature) in PHP or MySQL. However, I’m inclined to think it’s the latter, and I’ll get to why in a moment.

But first, some background. The table that SASHA uses to store schedules uses the BIT field type for keeping track of which days of the week a schedule occurs on. I figured it’d be easiest to use a 7-bit field and just flip a bit for each day of the week. And that worked fine for me on my local test server. But then I had a colleague test SASHA out on his test server, and things went a little wacky.

It took a little while to figure out what was causing our problem, and we finally got to the bottom of it: I was using MySQL 5.0 and he was using MySQL 5.1! Apparently, between 5.0 and 5.1, the return format of a BIT field changed from the literal binary data (output in the browser as a character, because the browser didn’t know it wasn’t) to a decimal representation of that data.

The first problem with that was that I had no idea there was a possibility of getting anything but the raw binary data I was getting on my server. The second problem was coming up with a straight-forward solution to detecting whether the database was feeding us raw binary data or converted decimal data. There was no direct way to do this, but I figured out the next best thing. A simple way to check what kind of data we’re getting is to find out whether it converts cleanly to an actual character. Here’s an excerpt from SASHA that demonstrates:

// MySQL 5.0 returns bit as binary, while MySQL 5.1 returns decimal
if( $days == chr( ord( $days ) ) )
	$input = 'binary';
	$input = 'decimal';

That seems to do the trick when it comes to handling unpredictable BIT field data.

(Again, I can’t guarantee that this isn’t actually a PHP issue, but I seem to recall us both being around the same version of PHP.)

If you have any insight into the matter, please do leave a comment.

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My Foray into Mozilla Education

Posted by Gordon P. Hemsley on February 14, 2009

I’ve recently rebooted this blog based on a suggestion by David Humphrey (humph) of Mozilla Education (wiki) during a discussion in #education. I’ll now be using it blog about my endeavors across the Internet related to software development (particularly the open source kind), as well as any other coding experiences I may have (including website development).

I’m excited to get involved with Mozilla Education, because that means I’ll be able to put my new Linguistics major to work (I’m currently attending the University of Vermont), while also building upon my 10 years of web development—not to mention being able to contribute to a community that I’ve been following and wanting to get involved with for those same 10 years. (I used Netscape 4 back in the day, was thrilled when Netscape 6 came out, soon switched to Mozilla Application Suite, and was finally convinced to switch to Firefox, where I’ve been ever since.)

In the coming days and weeks, I’ll be working with humph and others to decide where I’ll best fit. He suggested that I start with getting familiar with Ubiquity, so that I can perhaps help with their development of their natural language processing engine. He also mentioned the possibility of improving the tools that the localization team uses to translate Mozilla products into languages other than English, particularly via the Web. In the meantime, though, I have to brush up on my JavaScript, because it is an integral part of most Mozilla products, especially Ubiquity.

So I hope this will be a good experience for me, and I hope that I will be able to contribute something that other people will consider useful in the course of their using (or developing) Mozilla products.

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