Anything beyond HTML forms, a SQL database, and maybe a bit of Javascript and CSS is likely to be more complexity than you need for something like this.
And to query to SQL database from the JavaScript in the frontend web app? How do you plan to do this? You can't write an SQL query directly from the frontend web app.
So you need a backend framework, or at the very least a programming languages that can serve HTTP and has a driver for whatever DBMS you're using. Either using a language with a full-featured network standard library like Go, or else a simple framework like Flask or Sinatra would make things easier, or even Rails or Django, etc.
And is frontend validation enough? Or do you need backend validation as well?
And what about authentication? Are you leaving this wide open on the company intranet? Do you need an ACL? Most line of business apps of this kind do, often for regulatory reasons.
Logging? Also frequently required in line of business apps for auditing or regulatory reasons.
Perhaps you were assuming the existence of a backend programming language and these common features, but even simple apps like this can quickly involve much more complexity than originally anticipated, without at all going overboard.
Yep that's pretty much it: forms over data, in various domains.