ok thank you chaley, i will look at comments...
but i comfess that it seems very difficult to me !
So... I will ask you and the community my needs :
1) I want to feed a personnal field with the number of books of the serie it is part of.
2) And a true/false one which would be true if a same serie number is found in its serie.
3) And finally, is it possible to execute a python script on selected books only ?
If Calibre has to be off to execute a script, maybe the script should be executed for my books with my flag "treated" at false (or playing with the date but... in a next step
).
Thanx for your patience...