I’ve been running my “T-Comm” Bus Locator website for over seven years now. As a quick recap, on the backend, it’s a procedural PHP/MySQL website, kind of a typical thing one would see of PHP development circa 2000s. The high level overview is that every minute or two, the system polls TransLink’s real time information APIs for the locations of the all the buses in the system. The system then calculates some information based on TransLink’s GTFS data, which has the schedule information for the entire system. Then it saves the data into a MySQL database, and some other outputs Continue Reading
At work, we have been receiving reports of people, particularly on Android 2, not being able to install from the Google Play Store citing an error message “Package file is invalid“. At the same time, I was trying to test one of the features I was developing on a couple of Android 2 test devices we have in the office, but I was repeatedly getting an INSTALL_FAILED_DEXOPT error from adb. It seemed that both of these issues could be related.
Yesterday I fell into a very simple but dangerous SQL trap. Can you identify it? Found it? It’s the comparison to null. My intention was to get rows where another_column was null, however the query did not do so. It didn’t give me any results where another_column was null, but didn’t give me any error either. Why? Null in SQL is not a real value. Null means “lack of a value” or “unknown”. Anything compared to null leads to an “unknown” result. Therefore, in SQL there are actually three values conditions can evaluate to: true, false, and unknown/null. This is called Continue Reading
I’ve been using Sofa Control for my Apple Remote since I bought my Mac in 2009. I use Sofa Control pretty much every week when I volunteer with the youth ministry at my church. The Apple Remote by itself only works with certain programs that are designed to handle its input and it lacked support for other programs we were using such as OpenSong, which we use for song lyrics. So I bought a license for Sofa Control. Recently Sofa Control’s move to the App Store required all existing customers to repurchase the license. I didn’t want to shell out another Continue Reading