One of the key objectives – though not ulterior motives – in Service Oriented Architecture is decoupling. By decoupling currently mutually dependent agents, we introduce more opportunity for flexibility, no-impact optimization, reuse and interoperability. This does not require Web Services and the world of WS* to realize. Even with fairly simple database means, we can establish some nice decoupling. Right here in SQL.

This article introduces a rather thorough case of decoupling. An example of executing a SQL Query that does not hit a table. The query addresses a View and returns data, without ever touching a table. The View supports DML and will reflect the results of the DML in subsequent queries. However, no table is used at all. The View is a complete decoupling mechanism that absorbs the query, turns it into a PL/SQL call and returns the results from PL/SQL. Through an Instead Of trigger, it does the same thing for DML. So when you are looking for decoupling – and you ought to be – look no further than to this simple, straightfoward View example.

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