If you're using the KIM (Kentico Installation Manager) you have options at the last step to choose if you upgrade code or SQL or both. Another option is to download the upgrade package and just run the SQL script in the nested folders. Either way you still need to run the site after the upgrade has been performed on the db with the upgraded code. Also know if you don't have the proper upgrade .zip file in the CMSSiteUtils/Import directory, the upgrade will fail as well.