Structured Query Language (SQL)

Book excerpt: The Structured Query Language, SQL, has emerged in recent years as the standard query language used with relational databases. The SQL language has gained ANSI (American National Standards Institute) and ISO (International Standards Organisation) certification and a version of SQL is available for almost any computer system, from a Cray supercomputer to a PC. There is now a growing need for a clear, basic introduction to SQL and its applications. The author sets the scene with an introduction to relational databases and a brief history of the development of SQL. The language is then presented in an overview chapter which describes the functions of the major SQL commands and gives the reader an idea of the power of the language in creating, populating, querying and modifying database tables. Later chapters focus on explaining each of the SQL command groups more fully. The order of topics is carefully chosen as many SQL commands build upon others.