> You are encouraged not to implement all the business logic in the web application (i.e. your script), instead do it in the database schema using views, triggers or rules. If the system evolves, new ports will be intended to open to the database, and you have to re-implement the logic in each separate database client. Over and above, triggers can be used to transparently and automatically handle fields, which often provides insight when debugging problems with your application or tracing back transactions.
This is exactly the other way around. SQL code is difficult to debug, it lacks common programming language features and is more cumbersome to write and to deploy. You definitely should not implement your business logic in a Query Language, regardless of how Structured it is.