♣13♣RDBMS
In a nutshell, a relational database management system (RDBMS) is a set of tables (rectangular data),where each piece of information is only stored once and where relations are used to find the information needed. Usually, they are accompanied by an intelligent indexing systemthat allows searching in logarithmic times.
Consider a simple example that will demonstrate the basics of a relational database system. Imagine that we want to create a system that governs a library of books. There are multiple ways to do this, but the following tables are a good choice to get started:
- Authors, with their name, first name, eventually year of birth and death (if applicable) – A table of authors: Table 13.1 on page 220;
- Books, with title, author, editor, ISIN, year, number of pages, subject code, etc. – A table of books: Table 13.2 on page 220;
- Subject codes, with a description – A table of genres: Table 13.3 on page 220.
The tables have been constructed so that they already apply with some principles that underbuild relational database systems. For example, we see that certain field from the Author table are used in the Books table. This allows us to store information related to the author (such as birth date) only once. The birth-date is necessarily the same for all books authored by this person, because the birth-date depends only on the person.
Indeed, this simple example, with only three tables, shows right away some interesting ...
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