A database is an organized, machine-readable collection of symbols, to be interpreted as a true account of some enterprise. A database is machine-updatable too, and so must also be a collection of variables. Furthermore, a database is typically available to a community of users, with possibly varying requirements.
The organized, machine-readable collection of symbols is what you observe if you examine a database at a particular point in time. It is to be interpreted as a true account of the enterprise at that point in time. Of course it might happen to be incorrect, incomplete or inaccurate,
so this depends on the perception of the person looking at the data.
The alternative view of a database as a collection of variables reflects the fact that the account of the enterprise has to change from time to time, depending on the frequency of change in the details we choose to include in that account.
The suitability of a particular kind of database (such as relational, or object-oriented) might depend to some extent on the requirements of its user(s). When E.F. Codd developed his theory of
, he sought an approach that would satisfy the widest possible ranges of users and uses. Thus, when designing a relational database we do so without trying to anticipate specific uses to which it might be put, without building in biases that would favor particular applications. That is perhaps the distinguishing feature of the relational approach, and you should bear it in mind as we explore some of its ramifications.
E-commerce businesses (sometimes called e-tailers, rather than retailers) are prime examples of database-driven Web sites.
The data in an e-commerce site must be available for commerce to occur. A database crash could be disastrous for the e-tailer.
In addition, the data must be uncompromised and secure in both sending and receiving. Corrupted data and the complications it would create understandably would leave customers disgruntled, angry, and unlikely to return to that site.
Data security is vitally important because most e-commerce transactions include an exchange of credit card information.
In the next lesson, you will learn about the different technologies used to connect databases to the Web.