Oracle SQL: the Essential Reference

Programming and Data Access Languages

General-purpose programmable computers were first developed during World War II for military applications. The UNIVAC I, the first commercial general-purpose machine, was delivered in 1951. Several generations of programming languages have been developed since that time. Each generation has improved the productivity of programmers by automating mechanical tasks, allowing a programmer to concentrate on the higher-level concepts related to the application.

The earliest programs were written in machine code—the numbers corresponding to the instructions the programmer wanted to store in the machine's memory. Assembly language, which allowed the programmer to use names instead of numbers for instructions and memory locations, was developed in the early 1950s. The development of higher-level programming languages represented a significant step in raising the semantic level at which programmers work. A succession of such programming languages were invented, from Fortran (1957) to C (1972) to Java (1995), and their history is marked by a succession of growing and fading popularity. In addition to Fortran, C, and Java, Algol, COBOL, Ada, C++, and Basic are just a few of the important languages we have used to develop applications and systems programs.

In contrast to this plethora of procedural programming languages, today there is only one widely used data access language: SQL. SQL is a non-procedural data access language, as it leaves to the database ...