I've personally seen a building with a fractional street number, in Kingston, Ontario, Canada. I've also had to deal with irregular addresses in Canada. Working on a Canada-only program, I was expecting addresses to have the components:

[unit-number, ]building-number street-name
city/town, province/territory, country
postal-code

I was fortunately already expecting characters from the two official languages of Canada, English and French, so I was prepared to deal with accented characters.

Later, I had the opportunity to work in Iqaluit, Nunavut, Canada, which violated most of my assumptions, both explicit and implicit. First, the territory (not province) of Nunavut is a relatively recent creation, having been created by splitting off a part of the Northwest Territories on April 1st, 1999. Before that, the addresses were all in a different territory.

Second, Iqaluit uses a system where every building in the city has a unique number. Currently (2015) the highest number is rapidly approaching 7000, but at the time it was in the 5000s. In addition to their unique number, some buildings also have a name, which is sometimes written only in the Latin alphabet, sometimes written only in the Inuktitut syllabary, sometimes either, and in at least one case both. When a building has both a name and a number, people may use just one or the other. (I haven't found a building without a number yet, but I'm no longer going to assume there aren't any.)

Street names were not introduced until 2003, and when they were, all street signs were labeled in both the Latin alphabet and the Inuktitut syllabary. Since the system of uniquely numbering every building is continuing, most people ignore the street names unless they're actually talking about streets, not buildings. Nonetheless, some attempts have been made to get everyone to change their mailing addresses to include the street. In every case, everyone has agreed that use of the Inuktitut syllabary should be encouraged.

All these peculiarities are in the territorial capital, where almost all the territorial government and law-enforcement addresses are, so anyone dealing with addresses for the Canadian government should be aware of this (but probably isn't).

On a related topic, the US has long had a system of two-letter abbreviations for its states, commonly used in its addresses. Canada eventually introduced a standard set of two-letter abbreviations for all its provinces and territories, being careful not to duplicate any of the US state abbreviations. However, many people still use the traditional abbreviations, which are of variable length, sometimes have completely different French and English versions, and sometimes include hyphens to prevent confusion with US state abbreviations. (So 'T-N' might appear, meaning 'Terre-Neuve', the French name for Newfoundland, with the hyphen mandatory to prevent it from being mistaken for the US abbreviation for Tennessee. Periods and capital letters with accents also appear, e.g. 'Î.P.É.')

Since its introduction, the "standard" two-letter system has seen at least three name changes. Quebec was PQ before 1991 and is now QC, although sometimes QU or QB show up, Nunavut was added in 1999 (previously part of NT, now NU), and Newfoundland changed its name to Newfoundland and Labrador in 2001, and its abbreviation from NF to NL in 2002. Also, the territory formerly known as "Yukon Territory" officially changed its name to just "Yukon" on April 1st, 2003. (What is it with the Canadian territories and changing important stuff on April 1st?) Their postal abbreviation did not change however. It's still YT, not YK, despite the latter being used fairly often and making more sense now.

This matters because not all two-letter abbreviations appearing in the database (this includes your database) are on the standard list, either because they were entered incorrectly, or because they were correct when they were entered, but have since changed, and the database wasn't updated for fear of breaking working code. As a result, a naive lookup-table to get the full province name from the two-letter abbreviation will fail.