Managing & Using MySQL, 2nd Edition

Relational Databases

In the simplest terms, a database is a collection of data. An example of a nonelectronic database is the public library. The library stores books, periodicals, and other documents. When you need to locate some data at the library, you search through the card catalog or the periodicals index, or maybe you even ask the librarian. Those unsorted piles of papers on your desk also form a database. This database can potentially work, because the size of the database is incredibly small. A stack of papers certainly would not work with a larger set of data, such as the collections in the library. The library would still be a database without the card catalog, periodicals index, and librarian; it would just be an unusable database. A database generally requires some sort of organization to be of value. The paper pile, for example, is of greater value when organized into filing cabinets. So, restating our definition, a database is an organized collection of data.

The library and the stack of papers have many similarities. They are both databases of documents. It makes no sense, however, to combine them because your papers are interesting only to you, and the library contains documents of general interest. Both databases have specific purposes and are organized according to those purposes. We will therefore amend our definition a bit further: a database is a collection of data that is organized and stored according to some purpose.

Traditional paper-based databases have ...