Chapter 1. SQL, Vendor Implementations, and Some History
In the 1970s, IBM developed a product called SEQUEL, or Structured English Query Language, which ultimately became SQL, the Structured Query Language.
IBM, along with other relational database vendors, wanted a standardized method for accessing and manipulating data in a relational database. Over the decades, many competing languages have allowed programmers and developers to access and manipulate data. However, few have been as easy to learn and as universally accepted as SQL. Programmers and developers now have the benefit of learning a language that, with minor adjustments, is applicable to a wide variety of database applications and products.
SQL in a Nutshell describes four implementations of the current SQL standard, SQL99 (also known as SQL3): Microsoft’s SQL Server, MySQL, Oracle, and PostgreSQL. For those migrating from implementations of the earlier SQL standard, this chapter describes the current SQL standard and the ways in which it differs from the earlier standard. This chapter also provides a bit of history of the standards evolution.
The Relational Database Model
Relational Database Management Systems (RDBMSs), such as SQL Server and Oracle, are the primary engines of information systems worldwide, particularly Internet/Intranet applications and distributed client/server computing systems.
An RDBMS is defined as a system whose users view data as a collection of tables related to each other through common ...