I'm not sure if this is really unit testing - it's more system testing. My understanding of unit testing is that you are looking at a specific routine (or maybe stored procedure) and ensuring that the results of that routine are as expected. Unless you spend time creating check SQL to ensure that the call to the SP has done what you expect, then all you are doing is syntax checking in case of database schema changes, and maybe performance testing.

However, it is very useful to do a full system test, so I can see big advantages in this in that you need only run through a system test once (the first time and whenever there are logic flow changes) and then re-run it in the future as part of a pre-deployment test, saving time and effort.