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Object-Relational Mapping - Taking the Horror Out of Data Access

What are the benefits of using object relational mapping as persistence mechanism rather than .NET DataSets? Real-world use shows that developers who choose to work with persistent objects make more robust, scalable and maintainable software. By using object relational mapping you can still access data by connecting directly to the RDBMS, unlike choosing an OODBMS. There is a lot to be gained by using O/R mapping technology, and this article just talks about this.


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Object-Relational Mapping – Taking the Horror Out of Data Access

1. Horror stories and the object data divide
Let’s face it, the world is getting more and more OO, but we are still pretty happy with our relational databases. In fact the RDBMS is the foundation upon which basically all of our data driven applications reside. Having said this we are pretty aware of the fact that the relational data models we deploy are limited. Sometimes they aren’t much more than a bunch of tables that are increasingly cursed due to limitations and design flaws.



To develop great applications, we need a solid foundation based on a great data model, a data model that should matches real life as closely as possible, the so called domain model. How many database schemas actually resemble the real-world problem? Data access has become a time-consuming horror story that can take the fun out of any development project. But it doesn’t have to be this way.

2. Benefits of OO in stateless business methods
Even though relational theory is great for storing and retrieving large amounts of structured data, it hardly makes for readable business methods. The reason being that the relational data model contains very little information (despite what the name implies) about the relationships and intended use of the data. It has a low level of abstraction in the same way as C compared to VisualBasic. A properly implemented object-oriented data model on the other hand gives you the full picture and allows business methods to contain more straightforward, readable, code. Comparing two code snippets proves our point. The first code snippet interfaces the relational data model through SQL, the second interfaces the object-oriented data model through OO-notation (in this example we use the API of an O/R DAL generated by Pragmatier Data Tier Builder, se reference at the end of this article):

Public Sub GiveRaise(ByVal ConnStr As String, _



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