In one of my gigs, it was normal operating procedure to put logic in sprocs and call out to that from elsewhere. It makes so much sense - RDBMS engines are good at doing math, so we should let them do as much math as possible. ORM layers hide that away, and thinking about these problems in Ruby or Python work, but those languages just aren't as good at plain math as a database can be. I've done this type of thing in Rails and Express apps, and it makes complete sense there. You can even keep the sproc in source control by creating and changing them as migrations. It's tops.