On AniDB I can enter dd.MM.yyyy or yyyy-MM-dd (text input), which I like a lot. I often prefer reading and writing yyyy-MM-dd.

Some time ago I changed my Windows number format settings to show me yyyy-MM-dd formats. Unfortunately, that broke my webbrowsers date input / datepicker. :( So I had to go back to the standard culture format (de in my case).

The worst is when you work with dates and don’t know what is what, or when the behavior is unexpected.

Probably everyone knows about the Excel shitshow of implicitly converted values.

In SQL Server, what do you think 0000-00-00 is when converted to a date, explicitly or implicitly? Well, unfortunately, yyyyMMdd is a safer format than yyyy-MM-dd.

SET LANGUAGE 'us_english'
SELECT CONVERT(date, '2025-12-13')
--SELECT CONVERT(date, '2025-13-12') -- err
SELECT CONVERT(datetime, '2025-12-13 07:00:00')
--SELECT CONVERT(datetime, '2025-13-12 07:00:00') -- err

SET LANGUAGE 'Deutsch'
SELECT CONVERT(date, '2025-12-13')
--SELECT CONVERT(date, '2025-13-12') --err
--SELECT CONVERT(datetime, '2025-12-13 07:00:00') --err !!
SELECT CONVERT(datetime, '2025-13-12 07:00:00')

No, yyyy-dd-MM is not a common or valid German date format. That’s usually dd.MM.yyyy.

But worst of all, it changes behavior of the date parsing between date only and date + time types.