How to write Date and Time string in the same format as it was read?

[alpine]

@Zvoni
I'll absolutely agree with you, the only right thing that can be done is for OP to put a date-stamp format config into, either on  the application level or for a specific import source. And to include a mandatory dialog asking for it.

Thus, the TRon stance (which we all share, I believe) and the wp explaination, are coming to explain to the OP  (part) of the difficulties working with date/times in programs.

Not to mention that there are issues with such a strings even into the RTL ScanDateTime function, namely z format character - it scans ambiguously numbers of length 1 and 2: https://gitlab.com/freepascal.org/fpc/source/-/blob/main/packages/rtl-objpas/src/inc/dateutil.inc#L2697

The moral for the OP is: be very careful how you process date/time data in you program and prefer to ask the user instead of pretending to be a smart-ass.

[Thaddy]

The only and yes, the only correct way to store a date and time in a database as a string is in YYMMYYYY format and in UTC. For databases that support is, store the datetime as double. You correct the date and time to your local format o read. Really funny that nobody gave the correct answer....

[Zvoni]

The only and yes, the only correct way to store a date and time in a database as a string is in YYMMYYYY format and in UTC. For databases that support is, store the datetime as double. You correct the date and time to your local format o read. Really funny that nobody gave the correct answer....

Funny how Remy gave that answer already, and TS explained why he can't use it

The best solution would be to use a locale-independent format, like ISO-8601, eg: 2023-12-30T22:09:08

File CSV is obtained from external system which is out of my control. I can't set ISO-8601 date format in it.
The same with my output file: it is supplied for further processing by customer. Format should be preserved.

Sure, you could use FormatDateTime(), if you know which format you want to use. That means you need to parse the input string to determine its formatting.  Standard routines won't help you with that.

I see, thanks.