Is it possible to export played time per character per day to csv file?
I need something like date | character name | played time in seconds
and export this into desktop with in game chat command

It should be possible, and a useful feature IMO. Maybe, to have a more generic and consistent use, I would make the csv file to contain the data on a per-session basis, like:

Date | Character | Session start time (e.g. 3 P.M) | Played time

This way, session-related data can be obtained, but also if you wanted to have the played time per character per day you could still get it with few database queries.

I will try to implement it in the coming days, thanks for proposing it!

Let me know if you have any other comments about this.

I have released a new version with a similar feature to the one proposed.
The thing is that the WoW locks out certain functionalities of the Lua language to avoid instabilities. Writing files to disk is one of them. Therefore, my workaround has been to display an in-game textbox containing the sessions' data in CSV format from which the user can select and copy all the text displayed. Then, it would be the responsibility of the user to paste and save it into a new CSV file.

Thanks for your suggestion!