Updating tags for Item - How to do?

Hello everybody.

I m starting to use tags. While assigning tags at beginning is OK, I got some problems to updated tags in case the user wants to modify the tags on the selected item.

I followed the How-To, I created the data details area and the api that retrieve the tags for the item.
I made the form with a database update made like this:

Schermata 2022-12-20 alle 09.31.18957×608 69.9 KB

“estratto” is the table who contains the items to which tags will be associated.
“tags” is the table who contains the Tags names.
“estrattotags” is the subtable which contains IDs for estratto and for tags

as $_POST variables I set

I tried to set S_POST as array too but I always fgot ERROR 500.
Any hint please ?