Support for usernames that span two columns

My database stores usernames in two columns. There is a local part (alex) and domain part (example.com) which together form the username alex@example.com.

I have been looking into the source code of the user_sql app, but adding this seems rather complicated¹, because firstly the UI has to be changed to allow one and two column usernames and secondly some of the queries need to be changed as well. Also, although I have a view that returns the concatenated username, the app only allows databases to be specified, verifyTable() in lib/helper.php makes sure of it.

Finally I don’t quite understand the specification of the hash as products and not as crypt shemes.

What I would like to ask is how complicated you think implementing this feature (username spans two columns) would be in user_sql.

I looked into creating a new app where I can specify the raw SQL for each user property and while this seems more complicated at first it allows for almost endless possibilities and would be probably a pretty easy app compared to the existing one.

What do you think?

¹I have little experience with php and none with apps for Nextcloud.

I solved this problem by creating an app that can authenticate users and does other user management through user defined SQL queries. I can now specify whatever SQL scheme I use.

In case someone else has the same problem, here is the app: https://apps.nextcloud.com/apps/user_backend_sql_raw