Welcome to a dive into the Web morass in search of zero-cost, non-commercial, registration-free resources aimed at uncovering practical information about relational databases.
Organizing a collection of data elements in a logical manner is what converts them into a database. Although data stored in a single spreadsheet might constitute a rather primitive database, what makes a database relational is a particular way of organizing the data pieces into normalized tables. Doing so permits large quantities of data bits to be accessed and reassembled to produce useful output without having to reorganize the database tables themselves. Furthermore, a normalized database eliminates redundancy and the possibility of making errors each time the beast is updated.
Dr. Edgar Frank "Ted" Codd, IBM Fellow of the San Jose Research Laboratory, invented the relational database in 1970. If you go to the Web page posted by Paul Maxim, a graduate student at the University of Wyoming http://www.cs.uwyo.edu/~paulmax/cosc5000/codd_files/frame.html you'll find a brief biography of Mr. Codd, a list of the awards he's received and more. Codd is quite a guy.
The details that underlie databases and the construction thereof make use of many unique terms and concepts, but it's not exactly rocket science we're talking here. It's more logic and organization. Nevertheless, before you get too deep into this field, it would be worth your while to learn the jargon. To that end, you should visit http://www.dhdursoassociates.com/glossary.html, where you'll find a glossary posted by D. H. D'Urso & Associates.
But now that I think about it, even rocket scientists need databases. The Glossary of Database Terminology is a richly-linked document published by the Harvard-Smithsonian Center for Astrophysics, High Energy Astrophysics Division. Click on the technical words in a definition, and you move to a definition of the technical word, which contains additional technical terms. The glossary is reasonable comprehensive, but the risk is getting into a circular searchA means B, B means C, but C means A. And you never figure out what A really means using common words. Other than that, this site is worth your time. Visit http://hea-www.harvard.edu/MST/simul/software/docs/pkgs/pgsql/glossary/glossary.html .
Structured query language, SQL, is the interactive programming lingua franca for getting information from and into a relational database. Like so many software concepts and products, when a new version of SQL appears, its ultimate fate is to be supplanted by a later revision. Searching for relevant Web sites for this article uncovered references to SQL versions 2.0 through 4.66, which might not even be the most current. Make sure you're learning about the version you have available.
With that said, you probably should learn something about SQL if you're going to develop a customized database. To that end, I'd suggest paying a visit to http://www.cs.unibo.it/~ciaccia/COURSES/RESOURCES/SQLTutorial/sqlcont.htm, where you'll find a complete self-paced tutorial.
From the Ivory Tower
Christopher W. Clifton, Associate Professor in the Department of Computer Sciences at Purdue University, West Lafayette, Ind., offers 20 pages of class notes for a graduate-level computer science course. There's little explanatory text in this material that focuses on the underlying database logic and theory. It may be disconcerting to some to have to deal with Boolean and other symbology that's used to get across what you need to learn. This isn't a cookbook that shows how to do the deed using some particular software. It's not for everyone, but it's good. Look for CS 541 Review at http://www.cs.purdue.edu/homes/clifton/cs541/Review.pdf.
Database theory is a deep subject, but most of us use a database of one sort or another. If nothing else, we're all resident on some telemarketer's hard drive. Yes, anyone can use a database, and you can rightfully claim to be more than merely an appliance operator if you know something about the details concerning what's going on behind the keyboard of your CMMS and EAM systems. The next Web site could give you some info tidbits to spout off on the next trip to the water cooler. Read Characteristics of a Relational Database, a document posted at http://www.frick-cpa.com/ss7/Theory_RelationalDB.asp by David R. Frick & Company, Valencia, Calif. If you bother, you'll be rewarded with an explanation of Codd's 12 rules for a database management system, the engine that can make your very own data bits come alive.
Introduction to Relational Database Design by Fernando Lozano is an article that presents the basics of relational database design so that you can tackle ambitious database projects using mSQL or any other relational database operating under OS/2. Lozano even provides samples to run under mSQL and SQL Anywhere, but he doesn't attempt to teach the basics of SQL. Check out this document at http://www.edm2.com/0612/
This process arranges the data elements into individual tables that are then linked to eliminate redundancy and update errors.
A properly normalized database is constructed so that the individual customer information appears in only one place in one table. When the area code changes, the updated information is entered into your database only once. Then, when anyone queries the database, the only area code available for that customer is the correct one.