Implementation of Data Flow Query Language (DFQL)

Abstract

A relational database management system (RDBMS) is a software product that structures data in accordance with the relational data model and permits data manipulation based on relational algebra. There are two widely-used query languages for the relational database management systems (RDBMS's). These are Structured Query Language (SQL) and Query By Example (QBE). Although these languages are powerful, they both have drawbacks concerning ease-of-use, especially in expressing universal quantification and specifying complex nested queries. In order to eliminate these problems, Data Flow Query Language (DFQL) has been proposed. DFQL offers an easy-to-use graphical user interface to the relational model based on a data flow diagram, while maintaining all of the strengths of SQL andQBE. The purpose of this thesis is to implement DFQL, allowing the users to login one or more relational database(s) through JDBC, view the structure of the connected databases graphically, and implement inquiries in SQL and DFQL to retrieve the data.