Relational Completeness of Show and Tell Visual Programming Language

In this paper we present the database applications of the Show and Tell Language (STL) and demonstrate the relational completeness of the language. STL is a visual programming language designed for novice computer users who are not familiar with keyboarding. A program can be constructed by using only a pointing device, except for textual data entry. A program can be constructed by using only a pointing device, except for textual data entry. Various programming concepts such as subroutine, iteration, recursion, concurrency, exception, and so forth are represented by two-dimensional graphic patterns and icons. The language is used to test the feasibility of keyboardless programming, Currently the language is implemented on the Apple Macintosh personal computer. In this paper we will present, first, the Show and Tell language primitives, then simple database applications through examples, and finally the representation of the five basic operations in relational algebra; difference, union, Cartesian product, projection, and selection; all using the Show and Tell visual constructs. This demonstrates that STL is a visual relational data query language which is complete in the sense of Codd