DD/MM/YY and YY/MM/DD are the only acceptable ones IMO. Throwing a DD in between YY and MM is just weird since days move by faster so they should be at one of the ends and since YY moves the slowest it should be on the other end.
If you use DD/MM/YYYY, dumb sorting algorithms will put all of the 1sts of every month together, all of the 2nds of every month together, etc. That doesn’t seem very useful unless you’re trying to identify monthly trends, which is fundamentally flawed as things like the number of days in the month or which day of the week a date falls on can significantly disrupt those trends.
With MM/DD/YY, the only issue is multiple years being grouped together. Which may be what you want, especially if the dates are indicating cumulative totals. Depending on the data structure, years are often sorted out separately anyways.
YYYY/MM/DD is definitely the best for sorting. However, the year is often the least important piece in data analysis. Because often the dataset is looking at either “this year” or “the last 12 months”. So the user’s eyes need to just ignore the first 5 characters, which is not very efficient.
If you’re using a tool that knows days vs months vs years that can help, but you can run into compatibility issues when trying to move things around.
The ugly truth no one wants to admit on these conversations is that these formats are tools. Some are better suited to certain jobs than others.
I grew up with DD.MM.YYYY. But I think, MM/DD makes sense in everyday usage. You don’t often need to specify dates with year accuracy. “Jane’s prom is on 7th September” – it’s obvious which year is meant. Then it’s sensible to start with the larger unit, MM, instead of DD.
Even in writing you see that the year is always given like an afterthought: “7th September**,** 2023“.
I think most Americans do. Or at least it was taught that way in school when I was growing up. Maybe it’s because of the way we speak dates, like “October 23rd” or “May 9th, 2005”.
Regardless, the only true way to write dates is YYYY-MM-DD.
You only think it fits with how it’s read in English because that’s how you grew up saying it so it sounds natural to you. Your experience is not universal, and is in fact, a minority.
It’s how it is read in English (simplified) aka american english. Brittish english doesn’t do this nonsense, the talk in the correct format (first of january etc.).
(I’m sorry if i made some mistakes, english is my second language)
Japan is YYYY-MM-DD, but when we talk about dates where a year is unneeded, we just cut it off which leaves it in the US standard format of MM-DD, much to the annoyance of non-US foreigners living here.
YES! I wish more people knew about RFC 3339. While I’m all for ISO 1601, it’s a bit too loose in its requirements at times, and people often end up surprised that it’s just not the format they picked…
Huh, I’ve never noticed how much bloat was in ISO 8601. I think when most people refer to it, we’re specifically referring to the date (optionally with time) format that is shared with RFC 3339, namely 2023-11-22T20:00:18-05:00 (etc). And perhaps some fuzziness for what separates date and time.
I have autohotkey configured to insert the current date in ISO 8601 format into my filenames on keyboard shortcut for just this reason. So organized. So pure.
Download Autohotkey, and create a new script. Paste these shortcuts into the script and restart the script:
#NoEnv ; Recommended for performance and compatibility with future AutoHotkey releases.
; #Warn ; Enable warnings to assist with detecting common errors.
SendMode Input ; Recommended for new scripts due to its superior speed and reliability.
SetWorkingDir %A_ScriptDir% ; Ensures a consistent starting directory.
:R*?:ddd::
FormatTime, CurrentDateTime, yyyy-MM-dd
SendInput %CurrentDateTime%
return
:R*?:dtt::
FormatTime, CurrentDateTime, yyMMddHHmm
SendInput %CurrentDateTime%
Return
Now, if you type ‘ddd’ on your keyboard, the current date will be typed out, eg ‘2023-11-23’.
If you type ‘dtt’ tgen the datetime stamp will be typed out in YYMMDDhhmm format, eg 2311231012
There are so many cool things you van do with AHK to make your work more productive. For example, rather tgan typing your email address a billion times, add the shortcut:
::add1::your.email.address@domainname.com
And then you can type ‘add1’ and hit space, and your email address will be typed out in full. Of course, the string ‘add1’ can be whatever you want.
Lithuania is one of the Baltic States, conveniently squished between Russia & Belarus to the east and the sea to the west. Across that sea is Sweden. You’ll usually see three countries be the parts of this set. Lithuania is the southernmost of these three.
(This doesn’t consider the separator) Cyan - DD/MM/YY Magenta - MM/DD/YY Yellow - YY/MM/DD The other ones are mixes of those two colors, so e.g. the US is MM/DD/YY and YY/MM/DD (apparently).
Also just noticed I didn’t attribute this picture, I’ll edit my comment.
We are ridiculously inconsistent in Canada. I’ve seen all 3 of the most popular formats here (2023-11-22, 11/22/2023, and 22/11/2023) in similarish amounts. Government forms seem to be increasingly using RFC 3339 dates, but even they aren’t entirely onboard.
Funny thing, in ISO 8601 date isn't separated by colon. The format is "YYYY-MM-DDTHH:MM:SS+hh:mm". Date is separated by "-", time is separated by ":", date and time are separated by "T" (which is the bit that a lot of people miss). Time zone indicator can also be just "Z" for UTC. Many of these can be omitted if dealing with lesser precision (e.g. HH:MM is a valid timestamp, YYYY-MM is a valid datestamp if referring to just a month). (OK so apparently if you really want to split hairs, timestamps are supposed to be THH:MM etc. Now that's a thing I've never seen anyone use.) Separators can also be omitted though that's apparently not recommended if quick human legibility is of concern. There's also YYYY-Wxx for week numbers.
“I can reuse this old function if I just monkey-patch this other class to work with it, no one will have any issues understanding what’s going on”
Edit: Thought this was the programmerhumor community. For context: A monkey-patch is when you write code that changes the behaviour of some completely different code when it is running, thus making its inner workings completely incomprehensible to the poor programmer using or reading your code.
Had a coworker who used MMDDYY with no dashes. Unless you knew it was very hard to figure out, since it could also just be a number that happened to be 6 digits, too. At least YYYY-MM-DD looks like a date generally.
In many of them but not all, because it’s become convention and has been enshrined in their documentation policies. cGMP just requires that your quality management system has a policy in place that specifies how to document the date, and when exceptions are allowed (for instance, data printouts where YYYY-MM-DD is often the default).
It’s also the reason some labs require you to initial/date every page of printed data, and some only require you to initial/date the first and/or last page. I’ve seen FDA auditors be okay with both, as long as you can justify it with something like: our documentation policy defines the printout as a copy of the original data, and the original data as what’s stored on machine memory with electronic signature; versus: our documentation policy defines the original signed/dated data printout as the original data. In any case, it still has to follow 21 CFR part 11 requirements for electronic records & signatures, where the only date predicate rule example they give is 58.130(e), which itself is broad and only applies to non-clinical lab studies. It’s notable that the date format 21 CFR 11 itself uses is actually Month D, YYYY, with no zero padding on the day.
And if you don’t have IQ/OQ/PQ documentation showing how you locked down and validated the software’s ability to maintain an audit trail you can’t even use electronic records (or signatures).
Only within the same century, which is an issue for those of us born last millennium (or managing systems from that time), and could be a real problem in 50-ish years when we could get the first duplicates.
Better to stick with YYYY-MM-DD for alphabetical sorting
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