PHP Button to "save" post to database

Thanks for looking!

I have an issue where I would like the post id (p_id) to be saved to an SQL db when a button "Save" is clicked, and no data is entered.

The save button is on a page that has its own id, lets say 155. I would like the save button to send the id of the post to the db.

Any suggestions on how to complete this?

Not even looking for code, maybe just a pointer on the direction to take

Kind regards