Modeling the CODASYL DML context dependency for database program conversion

摘要

The CODASYL database (db) statements in an application program can have one or more different semantics associated with it, depending on the path through which the execution reaches that statement. This makes the CODASYL operations in a db program context dependent. The previous works on the db program conversion from the CODASYL record-at-a-time interface to the set-at-a-time interface of the relational model consider a limited class of programs where each db statement in the program is assumed to have a unique semantic interpretation. In this paper, we define a framework for analyzing the multiple semantics of the CODASYL operations and their context dependencies. We then show how the analysis can be used for converting a CODASYL db program which contains statements having ambiguous, multiply-defined semantics. The method described here allows us to convert any CODASYL db program.