Just about anything in which the SQL is considerably more complex or a lot longer than then the corresponding middleware code. Just about anything in which the

Just about anything in which the SQL is considerably more complex or a lot longer than then the corresponding middleware code. Just about anything in which the SQL query is considerably more difficult to debug or get intermediate verification than in the corresponding code. SQL does many things well. So far, it doesn't do everything as well as middleware code. It isn't as easy to use for every use case as middleware code. Long complex SQL queries are a nightmare to unravel. Middleware code can more easily (in my experience) be broken up into smaller steps that can be manipulated and tested independently.