by Joseph Love

Created on: May 22, 2008

Many years ago, when I was a very young programmer, I was introduced to Microsoft Access. Although it isn't the most complicated database in the world, the concepts that I learned in the simple Access program changed my career and even my life. Today, being an Oracle DBA with over 20 years of programming experience, I can remember the several eureka moments where I first began understanding databases. Understanding these principles enabled my mind operate in a realm I never knew existed, and projected me to the next phase in my career. I am now a DBA for an enterprise application in one of the biggest companies on earth, thanks to a few, now simple, concepts.

One of the first things I learned is that a database consists of lists of information. Like a spreadsheet, there are rows and columns, and unlike a spreadsheet, each column is required to contain the same type of data. For instance, if you were creating a spreadsheet of all the Cd's you own, you might use one column for the album name, another for the artist, another for the year, another for the cost of the album, etc. To do all of this, you would simply put in the title (or label) of each column in the first row. Subsequent rows would probably contain the actual information about each album you own. In a database, however, things would be a little different. First, you would have to define a table to store this information. You would add columns to the table, each having a specific data type. For example, you would create a table named "albums", with columns named Album_Title, Artist, Year, and Cost. The Title and Artist columns would be set to a "text" datatype, because they contain letters, and possibly numbers and probably aren't going to be used in mathematical formulas. The Year column, you could set to a numeric data type because it is only going to contain numbers, however, you could potentially use "text" or even "Date" datatype. The cost would definitely be set to a numeric datatype, since you might want to know the average or total cost of all your items (or, you would want to use this data in a formula).

The second thing I learned is that a database allows you to relate relevant information. Now suppose that you now want to make lists of the songs on each album you stored. If you've ever used a spreadsheet, you know that there are several options of achieving this, but all of them come with problems. In a database, this is no problem whatsoever. In a database, we simply create another table

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