Date custom column built from a Y/N one?

[glos]

Hi!
Is it possible to have a custom column that automatically detects the date another custom column was last modified?
I'd like to have a yyyy/mm/dd "Date Read" column coming from the date I've modified my Yes/No #read custom column. Though I imagine it's not easy also for the fact this is a Y/N/empty column, so with 3 values and I'd only need an entry for the Y one..
I don't even know if it's possible, if Calibre remembers when a particular column was modified or not... I'm definitely very far from being an expert, so I'm asking I hope the answer isn't under my nose

In any case, Thank you

[theducks]

There is a semi-hidden timestamp column: Modified (lookup:last_modified)
that records when ANY change that affects the books (eg. changing the case of a shared Tag that happens if a new book imports with a differing case of the tag) metadata

Sample search:

#read:true and last_modified:today

[chaley]

Sorry, but all calibre keeps is the date that *something* was modified.

You could do something like this manually if you kept two dates - one that is the reference date and one that is the changing one. You could then have a column that shows a checkmark (or something) if the changing one is later than the reference one. Of course, from time to time and according to your work flow, you would need to update the reference date to make the check mark go away. Not automatic. Perhaps not even usable.

If you have these two date columns then you could also use column icons or column coloring instead of the checkmark yes/no column.

[glos]

Thank you both!
Eh, I was almost sure the answer would be that (but one never knows, with calibre and its thousands of functions and tweaks), I actually used to sort by last modified date before I started a massive and ongoing cleaning of tags/pub dates/collections/insert-create covers/etc...
That messes up my library a bit because if months ago the last change was my check mark on the Y/N read column, now it can be something else, and my recently read books are buried and mixed with others (read and unread) that I modified recently.

I know about the manual date option, but at this point I should go back and guess when I read something and I really don't remember Kicking myself for not having thought about this immediately :/

Thanks for your answers!

*digress* column coloring: if I add more colors on my library it's really going to be a rainbow XD I got red for 5 stars, blue for books on reading lists, grey for books that i've read (so that they are less visible), another color I forgot for books I didn't like much, that makes them almost disappear from my sight, violet for WIPs, then I've got a couple others for collections... Seems confusing but it's really very helpful

Originally Posted by theducks

Sample search:

#read:true and last_modified:today

I'll keep in mind this though ! (I'm so bad at searching... glad that I've created a few VL with complex searches at least XD)