Mutability Key to Imperative Logic

The only reason imperative logic (a.k.a instructions) execute in sequence is that due to the presence of mutable stored values, the result is dependent on the evaluation order. Using your vocabulary, an "instruction" can (and a "rule" cannot) operate on mutable values. – Shelby Moore III

http://stackoverflow.com/questions/602444/what-is-functional-declarative-and-imperative-programming

Two-tier vs. N-tier

Two-tier approaches, while allowing more rapid development, are inherently less scalable than N-tier solutions (such as Web-based database solutions).[citation needed] In a two-tier solution, there must be one connection to the database for each concurrent user, whereas with N-tier solutions, which incorporate connection-pooling technology, a limited number of database connections - sometimes, just a single connection - are multiplexed among a much larger number of actual concurrent users.

http://en.wikipedia.org/wiki/PowerBuilder

Law of Demeter

The issue here is that LoginPage is breaking a the Law of Demeter. LoginPage is asking for the Database even though it itself has no need for the Database (This greatly hinders testability as explained here). You can tell since LoginPage does not invoke any method on the Database.

http://misko.hevery.com/2008/10/21/dependency-injection-myth-reference-passing/