Reference link for additional context: Sitecore upgrade from 8.1 Update-3 to 9 Update-1
@JayS: Regarding Sitecore Upgrade from Sitecore 8.1 to Sitecore 9.1, as suggested by you I am setting up a new instance of Sitecore 9.1 and upgrading the database of the existing website and after than I will point the new application to upgraded DB.
I have one question regarding upgrade of database: First we have to Execute scripts for the Core, Master, and Web databases (execute the
CMS_core.sql script for the Core database only) and after this I have to install the upgrade package using the Sitecore Update Installation Wizard. In the wizard, on the Analyse package page do we have to select only 'Install Items' and unchecked 'Install Files' as we are using fresh installation?