Database design has a huge impact on overall system performance, and the design of tables, indexes, storage, and memory can be a determining factor in the usability of the application, which is the ultimate goal of the system.
Normalization theory is an inseparable part of database table design. It is a topic that frequently appears in the Basic Information Processing Engineer and IT Passport examinations, even though it is an upstream process in system development.
While it is of course important to learn for scoring purposes, normalization theory is also a powerful weapon for determining the structure of data, which can be used for file layouts, structures within applications, and class design, and is a point that anyone involved in the system should keep in mind.
Well, enough of the nouveau riche....
Normalization theory explained in the question booklet for the Basic Information Processing Engineer and IT Passport examinations is explained in a fairly small amount of space for the sake of paper space, isn't it? This may be the reason why I feel that they give an impression of being difficult. When I myself first learned about it, I had a series of "? I had a lot of "what? On the other hand, specialized books explain things in a theoretical manner, but I feel that they are too academic and difficult.
Since I am an engineer, I will try to provide explanations that are as simple and practical as possible, as if I were a practicing engineer. I will try to keep the content simple, so I hope you will read it without hesitation.