Common programming idioms, for example iteration, are hard to express in a SQL query, and I think if you try to force iterative ideas on this declarative language the result is frustration or fear.

The need to be able to express yourself iteratively was a motivator for Microsoft's DryadLINQ - a programming language for distributed computation that has SQL-like constructs integrated into C#, giving you a high-level language with some of the declarative benefits as well as some of the imperative benefits (including more natural ways to express iteration).