Date of this Version
For a data management system with information storage and retrieval capabilities a language is needed by which a user of the system can specify the records he wishes to retrieve and the operations he wishes to perform on these records. The Command and Query Language under discussion was developed to meet these needs for the extended data management system. Its development was divided into two spheres of responsibility. The first sphere, referred to as the Assembler, centers on the routines needed for accepting and translating user requests. The second sphere centers on those routines needed for executing the translated requests. These routines are called collectively the Interpreter. The design of the Command and Query Language and the implementation of the Assembler is the topic of this report.
Basically, the Language enables the user to specify the records by means of the logical and arithmetic expression of keywords. Since program names may be keywords, the user can specify operations (to be performed on records) with keyword expressions as well The design of the Language involves the following steps:
(1) Define the requirements of the Language.
(2) Define the (external) syntax and semantics of the Language.
(3) Design an internal form of the Language to allow efficient processing by the Interpreter.
The design and implementation of the Assembler will result in the necessary routines which can check the syntax of the Language and transform the Language from its external syntax to internal form.
Jorge Gana, "A Command and Query Language Assembler for an Extended Data Management System", . April 1971.
Date Posted: 23 January 2008