Abstract

SQLEDDI is a purpose-built environment designed to support the study of relational theory and query languages, which is primarily intended for educational use. It studies the use of SQL in conjunction with EDDI, a definitive notation and a data manipulation language based on relational algebra, as a relational database query language.

As many other notations, the current SQLEddi notation is written using the agent-oriented parser developed by Christ Brown (2001), a style of parsing unique to Empirical Modelling. However, a later enhancement of the AOP referred to as aop_v204 implemented by Antony Harfield (2003) changed many behaviour of the parser, which brought motivations to write a new notation of SQLEddi that is able to function with the new improved version of the parser (aop_v204), especially after the modifications introduced to the Eddi parser and achieving a working notation of Eddi using the aop_v204.

Another good reason of writing the SQLEddi notation in aop_v204 (aside from what it offers of consistency and simplicity) would be the fact that the latter allows an AOP to execute scripts that call another AOP. Since the SQLEddi parser translates SQL into Eddi, which gives the user a choice of two notations for database management, it will be possible for the SQL parser to execute Eddi code in parallel with its own parser using the aop_v204.

The paper will be studying the SQLEddi environment and notation. It will investigate the behaviour of its parser before and after the modifications are made, which will make use of some of the documentations written by members of the Empirical Modelling group (See list of references). The paper will discuss some of the issues that may arise with the development of the parser (as the notation will be re-written) such as problems and limitations in the parser’s behaviour, and suggested solutions will be listed to overcome these limitations.