Do You Have a Date?

By Dr. Jeff Mirus ( bio - articles - email ) | Apr 19, 2012

If you’re working with “small” dates as a programmer, you might express today’s date as 2012-04-19. You might use that date as an identifier in a database if you were programming a system that would bring up particular information about particular dates. I’m talking about our “day” display in the liturgical year section.

Now let’s further suppose you wanted to count the number of times people viewed the pages for different dates. You might make up an additional little data table (call it “hit_counter”) in which a “count” field would be incremented each time a particular day was loaded. The correct record in that new table could be identified by the “small date”.

Now let’s add another supposition. You’ve already programmed a hit_counter system for your entire website, and the ID fields for every other kind of information on the site are simple numbers. The forty-thousandth news story has an ID of 40000. The thirty-ninth City Gates entry has an ID of 39. Each ID is keyed to its proper data table, of course. It works like a charm!

But when you add the liturgical days to this counting system, you forget something. You forget that the identifier for your days is a date, like 2012-04-19. And because you’ve forgotten this, you pass that value to your tried-and-true hit_counter routine as if it were a number, just like all the others. And then you wonder why the total hits for the various days of the year begin to look a little strange.

And you wonder. And you wonder some more. You pull your hair because you know the code works everywhere else. You start giving your email correspondents short shrift. You are late for dinner. You yell at your wife and kids.

Until, all at once, you realize the obvious.

When 2012-04-19 is passed as a number, it is passed as 2012 minus 4 minus 19. In other words, it is passed as 1989. And guess what? 2011-04-18 is also passed as 1989. As is 2010-09-12. Moreover, 2013-01-23 will soon enough be passed as 1989. And many other dates besides.

But, hey, I figured this out today, didn’t I?

And nobody died.