Best timestamp format for CSV/Excel?

Question

I\'m writing a CSV file. I need to write timestamps that are accurate at least to the second, and preferably to the millisecond. What\'s the best format for timestamps in

Answer 1

Given a csv file with a datetime column in this format: yyyy-mm-dd hh:mm:ss

Excel shows it in this format: dd/mm/yyyy hh:mm

e.g. 2020-05-22 16:40:55 shows as 22/05/2020 16:40

This is evidently determined by the Short date and Short time format selected in Windows; for example, if I change the Short date format in Windows to yyyy-mm-dd, Excel shows 2020-05-22 16:40.

Annoyingly, I can't find any way to make Excel show the seconds automatically (I have to manually format the column in Excel). But if the csv file includes a time column in hh:mm:ss format (e.g. 16:40:55), that's what shows in Excel, including the seconds.