Fourth generation language:
A programming language that can be employed directly by end users or less skilled programmers to develop computer applications more rapidly than programming languages.
This refers to a preliminary working version of an information system for documentation and evaluation purposes.
Facilities of 4GLs:
1. Query languages e.g. SQL
They could be used in retrieving data stored in databases or files in a prototype application.
2. Report generators e.g. RPG III
They extract data from files or databases to create customized reports in a wide range of formats not routinely produced by an information system. Report generators could be used to implement the reporting facility of a prototype.
3. Graphics languages e.g. SAS Graph, Systar
They retrieve data from files or databases and display them in a graphic format. Some graphics software can perform arithmetic or logic operations on data as well. Graphics languages could thus be used to implement prototypes, which prevent graphing features.
4. Application generators e.g. FOCUS, PowerBuilder
They contain pre-programmed modules that can generate entire applications including websites greatly speeding development. A user can specify what needs to be done, and the application generator will create the appropriate program code for input, validation, update, processing and reporting.
5. Very high programming language languages e.g. APL, Nomad2
They generate program code with fewer instructions than conventional languages such as COBOL or FORTRAN. They are designed primarily as productivity tools for professional programmers who may need to code a prototype in a short period of time.