As we said, a single-tiered application is just that, with everything thrown into a single tier. A multi-tiered application (or an n-tier application) is an application that is broken into different layers, each responsible for just part of the complete application.
Data is stored in the database.
All database access queries are stored in a special file. This file does no data presentation (it doesn’t generate HTML, for example) and all database access is via this file.
All presentation (the HTML and <cfoutput> blocks) goes in another file. This file doesn’t ...