Chapter 6. Introducing SQL
IN THIS CHAPTERUnderstanding Data Sources 2Creating A Data Source 3Preparing to Write SQL Queries 9Creating Queries 10Sorting Query Results 13Filtering Data 15SQLpronounced "sequel" or "S-Q-L"is an acronym for Structured Query Language, a language you use to access and manipulate data in a relational database. It was designed to be easy to learn and extremely powerful, and its mass acceptance by many database vendors proves that it has succeeded in both.In 1970, Dr. E. F. Codd, the man called the father of the relational database, described a universal language for data access. In 1974, engineers at IBM's San Jose Research Center created the Structured English Query Language, or SEQUEL, built on Codd's ideas. This language was incorporated into System R, IBM's pioneering relational database system.Toward the end of the 1980s, two of the most important standards bodies, the American National Standards Institute (ANSI) and the International Standards Organization (ISO), published SQL standards, opening the door to mass acceptance. With these standards in place, SQL was poised to become the de facto standard used by every major database vendor.Although SQL has evolved a great deal since its early SEQUEL days, the basic language concepts and its founding premises remain the same. The beauty of SQL is its simplicity. But don't let that simplicity deceive you. SQL is a powerful language, and it encourages you to be creative in your problem solving. You can almost always find more than one way to perform a complex query or to extract desired data. Each solution has pros and cons, and no solution is explicitly right or wrong.Lest you panic at the thought of learning a new language, let me reassure you: SQL is easy to learn. In fact, you need to learn only four statements to be able to perform almost all the data manipulation you will need on a regular basis.
