Welcome to the forums. 🙂

First, no, you can't call a procedure in-line of another SQL statement to run per row. Those are functions in SQL Server, and they're usually performance killers.

Secondly, if you show us the code you are using in your proc, we should be able to show you how to make it optimal for large queries and get you into some good practices. If you take a look at the link in my first signature, you'll see what we'd really prefer to help you get that working well.

In general, however, when you're working with quarters, weekends, holidays, etc, what we usually work with is a calendar table. Setting it up originally can be a bit of a pain but from there you can automate it to be kept up to date, and it solves a host of run-time computational problems, like determining a date's quarter for reporting.