When properly implemented, a relational database can greatly enhance the availability of data and information for an enterprise's decision makers. However, deploying a relational database on almost any scale requires a thorough understanding of the fundamental concepts and rules that govern their behavior.
Although my SQL is one of the most popular relational database applications available, that does not mean that it is immune from the complexities associated with the setup of a relational database. In their book, Get It Done With MySQL 5, Arthur Fuller and Peter Brawley describes the basics of using MySQL, including building queries and using the various built in APIs. Chapter 1, Relational Databases, available from TechRepublic, explains the fundamental concepts underlying relational databases, including sets, tables, Codd's 12 Rules, normalization, and the limits of the relational model.
In the following interview, authors Arthur Fuller and Peter Brawley discuss common problems enterprises must overcome when implementing a relational database and the future of MySQL as an open source application.
[TechRepublic] Relational databases can be a very powerful business tool if planned and deployed correctly. Unfortunately, all too often the implementation of these systems is not as good as it could be. In your experience, what are so many organizations missing when it comes to planning their relational databases? Is it one common shortcoming, or does it vary with each enterprise?
[Arthur Fuller] As Fred Brooks said, every significant program should be written twice: once to understand the problem and once to solve it. The main thing organizations of all sizes are missing is this: If the database is complex, you are guaranteed to get it wrong the first time. But it's hard for managers to accept this and factor it into their schedule.
[Peter Brawley] One reason nothing's as good as it could be is that database designs and programs are like novels: development's not finished, it's just abandoned at a point of diminished return.
There's one problem I often see: buying into the particularities of one system. It's entirely understandable; faced with multiple RDBMS implementations the organization picks one and hangs on for dear life. SQL standards were supposed to fix that, but could not. Every implementation has its limitations and weaknesses, and eventually those weaknesses can make for big trouble if the organization hasn't stayed light on its feet.
[TechRepublic] In the chapter excerpt, you state a principle for practical database design: "All primary keys shall be meaningless." Why is this so important?
[Arthur Fuller] To be fair about this, some data modeling experts disagree. Their argument is that a meaningless primary key (PK) models nothing in the real world. I agree with that statement, but in the applications I have worked on it is unimportant. Suppose, for example, you're selling eggs by the dozen and crate, or nuts and bolts, or DVD movies. Even if you could think of a way to individuate each instance, what good would it do? Do you really need to know which chicken laid which egg, and which slot in the egg carton that particular egg occupies?
Furthermore, PKs that embed meaning must be invented by the users. I have seen numerous databases where what seemed like good and clear rules for creating PKs turn out over time to have contradictions, ambiguities and inconsistencies. I have seen users sitting there scratching their heads trying to invent a new PK and duplicating existing keys again and again.
I tend toward the maxim, "Anything the system can do, the system should do." PKs are one example.
[Peter Brawley]PKs have a purely logical purpose: to numerically guarantee row uniqueness. No real-world datum can make that guarantee. If you use national id numbers (for example Social Security Numbers in the US & Canada), you have to deal with transcription errors and millions of fakes, if you use the t-shirt company's shirt codes, the company will eventually have to revise its coding, and so on: you wind up having to edit primary keys in parent and child tables, a no-no for many reasons.
[TechRepublic] MySQL is an extremely popular database application and is used by many enterprises in conjunction with their Web sites. How would you rate MySQL in terms of capabilities and features? Is MySQL best suited for particular applications? Is it not well-suited for others?
[Arthur Fuller] Perhaps the most outstanding feature of MySQL is its performance. Perhaps its weakest area is security. The MySQL team has responded to demands for stored procedures and views. This is the most important new development in several versions. Finally, you can't ignore the price. I wouldn't recommend that a production database be set up without a support contract, but even then the price is a small fraction of what Oracle or Microsoft would charge.
[Peter Brawley] Open source, price, performance, and the huge and extremely helpful user community are four reasons I think MySQL will be around for a long time.
[TechRepublic] MySQL has a storied history and is very popular, but are there other open source databases, perhaps more powerful or having more features, on the horizon? Will MySQL be as popular 10 years from now?
[Arthur Fuller] As Werner Heisenberg said, "Prediction is difficult, particularly of the future." Things change. Sybase has released a free version of its database. Borland has done the same with Interbase, and Computer Associates with Postgres. And who knows what revolutionary technology is being built in some basement as we speak? MySQL will be around for years. Whether it becomes the dominant database is as much a marketing question as it is a technology question.
[Peter Brawley]Can't add anything to that.
Download the free book excerpt, Relational Databases, for a more comprehensive examination of the basic relational database principles established by Dr. Edgar Frank Codd and for insight on how you can put those axioms to practical use in your next database project.
Mark W. Kaelin has been writing and editing stories about the IT industry, gadgets, finance, accounting, and tech-life for more than 25 years. Most recently, he has been a regular contributor to BreakingModern.com, aNewDomain.net, and TechRepublic.